C语言基础练习题初学者可参考
1.字符反转
#include
#include
#include
void swap(char *a,char *b)
{
if(a==NULL&&b==NULL){
printf("The ginseng error");
exit(EXIT_SUCCESS);//若为初学者此处用return ;也是可以的,不影响使用;
//exit 为退出这个进程
}
int temp=0;
while(a 2.输出所有小于100的质数
#include >
int main(int argc, char const *argv[])
{
int n=100;
int i=0;
int j=0;
int a=0;
for(i=1;i 3交换的方式三种
3.1第一种三杯水交换
#include
int main(int argc, char const *argv[])
{
int a=10;
int b=20;
int temp=0;
temp=a;
a=b;
b=temp;
printf("a=%d b=%d\n",a,b);
return 0;
}
3.2第二种异或交换
#include
int main(int argc, char const *argv[])
{
int a=10;
int b=20;
int temp=0;
a=a^b;
b=a^b;
a=a^b;
printf("a=%d b=%d\n",a,b);
return 0;
}
3.3第三种交换//注意越界数值不能太大
#include
int main(int argc, char const *argv[])
{
int a=10;
int b=20;
int temp=0;
b=a+b;
a=b-a;
b=b-a;
printf("a=%d b=%d\n",a,b);
4.练习： 1.设计一个程序，实现功能： 输入一个字符， 如果是大写的，就转换成小写的输出 如果是小写的，就转换成大写输出 如果是数字，就 * 10 输出 如果是其他字符，都输出 # a --> A B --> b 2 --> 20 ( --> #
#include
int main(int argc, const char *argv[])
{
char v = 0;
scanf("%c", &v);
getchar();
if (v >= 'A' && v <= 'Z'){
v += 32;
printf("%c\n", v);
}else if (v >= 'a' && v <= 'z'){
v -= 32;
printf("%c\n", v);
}else if (v >= '0' && v <= '9'){
v -= '0';
v *= 10;
printf("%d\n", v);
}else{
printf("%c\n", '#');
}
return 0;
} 5ifelse语句使用
练习： 编写程序计算身高 每个做父母的都关心自己孩子成人后的身高， 据有关生理卫生知识与数理统计分析表明， 影响小孩成人后身高的因素有遗传、饮食习惯与坚持体育锻炼等。 小孩成人后身高与其父母身高和自身性别密切相关。 设faHeight为其父身高，moHeight为其母身高，身高预测公式为： 男性成人时身高 = (faHeight + moHeight) * 0.54(cm) 女性成人时身高 = (faHeight * 0.923 + moHeight) / 2(cm)此外，如果喜爱体育锻炼，那么在原基础上可增加身高2% 如果有良好的卫生饮食习惯，那么在原基础上可增加身高1.5% 程序要求：父亲的身高与母亲的身高、小孩的性别、是否喜爱体育锻 炼 和是否有良好的卫生饮食习惯也从键盘上输入，最终输出预测的 身高。 提示：小孩性别的输入方式，可在屏幕给出提示“请输入小孩的性别 （男孩输入1，女孩输入0）：”， 然后通过if语句来判断从键盘输入的字符是1还是0。 是否喜爱体育锻炼也可以通过类似的方式实现。
#include
int main(int argc, const char *argv[])
{
double faHeight = 0;
double moHeight = 0;
double childHeight = 0;
double pe_temp = 0,food_temp = 0;//用来记录身高的曾量
int sex = 0; //性别 1男 0女
int PE = 0; //体育运动 1喜欢 0不喜欢
int FOOD = 0;//饮食习惯 1好习惯 0不好习惯
printf("请输入父亲的身高:");
scanf("%lf", &faHeight);
printf("请输入母亲的身高:");
scanf("%lf", &moHeight);
printf("请输入孩子的性别(1男生 0女生):");
scanf("%d", &sex);
if(1 == sex){
childHeight = (faHeight + moHeight) * 0.54;
}else{
childHeight = (faHeight * 0.923 + moHeight) / 2;
}
printf("请输入是否喜欢体育运动(1喜欢 0不喜欢):");
scanf("%d", &PE);
printf("请输入是否有好习惯(1有 0没有):");
scanf("%d", &FOOD);
if(1 == PE){
pe_temp = childHeight * 0.02;
}
if(1 == FOOD){
food_temp = childHeight * 0.015;
}
childHeight = childHeight + pe_temp + food_temp;
printf("预测的孩子的身高为:%.3lf\n",childHeight);
return 0;
}
6.简易计算器实现
.编写代码，实现简易计算器功能(操作数 是整数即可 + - * / %)： scanf("%d %c %d",); 输入：5 + 2 输出：7 输入：10 % 3 输出：1
#include
int main(int argc, const char *argv[])
{
int num1 = 0, num2 = 0;
char operator = 0;
scanf("%d %c %d", &num1, &operator, &num2);
switch(operator){
case '+':
printf("%d + %d = %d\n", num1, num2, num1+num2);
break;
case '-':
printf("%d ‐ %d = %d\n", num1, num2, num1-num2);
break;
case '*':
printf("%d * %d = %d\n", num1, num2, num1*num2);
break;
case '%':
printf("%d %% %d = %d\n", num1, num2, num1%num2);
break;
case '/':
printf("%d + %d = %.3lf\n", num1, num2, (double)num1/(double)num2);
break;
default:
printf("我仅支持 + ‐ * / %%\n");
break;
}
return 0;
}
7学生成绩等级管理
#include
int main(int argc, const char *argv[])
{
int score = 0;
scanf("%d", &score);
getchar();
switch(score/10){
case 10:
case 9:
printf("A\n");
break;
case 8:
printf("B\n");
break;
case 7:
printf("C\n");
break;
default:
printf("不及格\n");
break;
}
return 0;
} 8.使用while循环，实现 1~100 求和。
#include
int main(){
int i = 1, sum = 0;
while(i<=100){
sum += i;
i++;
}
printf("sum = %d\n",sum);
return 0;
} 9..猴子吃桃
#include
int main(){
int sum = 1;
int i = 0;
while(i<9){
printf("第 %d 天,有 %d 个桃\n", 10-i, sum);
sum = (sum+1)*2;
i++;
}
printf("第 %d 天,有 %d 个桃\n", 10-i, sum);
return 0;
} 10.水仙花
#include
int main(int argc, const char *argv[])
{
int i = 0;
int ge = 0;
int shi = 0;
int bai = 0;
for(i = 100; i < 1000; i++){
ge = i % 10;
shi = i / 10 % 10;
bai = i / 100;
if(ge*ge*ge + shi*shi*shi + bai*bai*bai == i){
printf("%d\n", i);
}
}
return 0;
}
11排版打出下面这种结果
#include
int main(int argc, char const *argv[])
{
char ch='A';
int i=0;
int j=0;
int a=0;
for(i=0;i<8;i++){
for(j=0;j 12.输入一个数，输出这个数的所有因子。
#include
int main(int argc, const char *argv[])
{
int num = 0;
scanf("%d", &num);
getchar();
for(int i= 1; i <= num; i++){
if(num%i == 0){
printf("%d\n", i);
}
}
return 0;
}
13完美数
#include
int main(int argc, const char *argv[])
{
int i = 0;
int j = 0;
int sum = 0;
for(i = 1; i < 1000; i++){
sum = 0;
for(j = 1; j < i; j++){
if(i%j == 0){
sum += j;
}
}
if(sum == i){
printf("%d\n", i);
}
}
return 0;
}
13练习： 1.定义一个10个长度的int数组，并全部初始化成0， 循环给数组成员赋值，赋的值来自键盘输入； 输出数组中最大的元素及最大元素的下标。
#include
int main(){
int arr[10] = {0};
int i = 0;
int max_index = 0;
for(i = 0; i < 10; i++){
scanf("%d", &arr[i]);
}
for(i = 1; i < 10; i++){
if(arr[i] > arr[max_index]){
max_index = i;
}
}
printf("max_value = %d , max_index = %d\n",arr[max_index],max_index);
return 0;
} 14冒泡排序
#include
int main(int argc, const char *argv[])
{
int s[10] = {23,45,65,78,90,55,33,17,96,54};
int i = 0;
int j = 0;
int temp = 0;
int flags=0;
int len = sizeof(s)/sizeof(int);
for(i = 0; i < len; i++){
printf("%d ", s[i]);
}
printf("\n");
for(j = 0; j < len-1; j++){
flags=0;
for(i = 0; i < len-1-j; i++){
if(s[i] > s[i+1]){
temp = s[i];
s[i] = s[i+1];
s[i+1] = temp;
flags=1;
}
}
if(flags==0){
break;
}
}
for(i = 0; i < len; i++){
printf("%d ", s[i]);
}
printf("\n");
return 0;
}
15strlen函数
#include
int mystrlen(char *num)
{
int i=0;
while(*num){
i++;
num++;
}
return i;
}
int main(int argc, char const *argv[])
{
char num[20]="i love china";
int length=0;
length=mystrlen(num);
printf("%d\n",length);
return 0;
} 16strcat
#include
void mystrcat(char *dest, char *src)
{
//1.判断地址是否是空，如果是空就退出
if(dest == NULL || src == NULL){
return ;
}
//2.找到dest的'\0'
while(*dest){
dest++;
}
//3.拷贝数据
while(*src){
*dest++ = *src++;
}
//4.给dest赋结束符号
*dest = '\0';
}
int main(int argc, const char *argv[])
{
char arr[50] = {0};
char brr[100] = {0};
printf("input string (arr) > ");
gets(arr);
printf("input string (brr) > ");
gets(brr);
mystrcat(brr,arr);
printf("brr = %s\n",brr);
return 0;
}
16strcpy
#include
#include
#include
char* mystrcpy(char* arr, char* brr)
{
if (NULL == arr || NULL == brr){
printf("传参错误\n");
exit(-1);
}
char* cp = arr;
while (*cp++ = *brr++);
return arr;
}
int main(int argc, char const *argv[])
{
char arr[100] = "asdasd";
char brr[200] = "112321312";
mystrcpy(arr, brr);
printf("%s\n",arr);
return 0;
}
17strcmp
#include
int mystrcmp(char *a,char *b)
{
while(*a&&*b&&*a==*b){
a++;
b++;
}
if((*a-*b)>0){
return (*a - *b);
}else if((*a-*b)<0){
return (*a - *b);
}else{
return 0;
}
}
int main(int argc, char const *argv[])
{
char a[20]={0};
char b[20]={0};
int flag=0;
printf("Please enter the value of a >");
gets(a);
printf("Please enter the value of b >");
gets(b);
flag=mystrcmp(a,b);
if(flag>0){
printf("a>b\n");
}else if(flag<0){
printf("a 18编写atoi函数
#include
void my_gets(char *a,int n)
{
int i=0;
while(i='0'&&(*s)<='9'){
num=num*10+*s-'0';
s++;
}
return sig*num;
}
int main(int argc, const char *argv[]){
char array[50]={0};
my_gets(array,100);
printf("%d\n",my_atoi(array));
return 0;
}
19斐波那契数列
#include
int main(int argc, const char *argv[]){
int s[20]={1,1};
int i=0;
for(i=2;i<20;i++){
s[i]=s[i-1]+s[i-2];
}
for(i=0;i<20;i++){
printf("%d ",s[i]);
}
puts("");
return 0;
}
#include
int feibo(int n)
{
if (n <= 2){
return 1;
}
return feibo(n - 2) + feibo(n - 1);
}
int main(int argc, char const *argv[])
{
printf("%d\n", feibo(8));
return 0;
}
20数组中找最大值
#include
int main(int argc, const char *argv[]){
int arr[10]={0};
int i=0;
for(i=0;i<10;i++){
scanf("%d",&arr[i]);
}
int max=0;
for(i=0;i<10;i++){
if(arr[i]>arr[max]){
max=i;
}
}
printf("%d %d\n",max,arr[max]);
return 0;
}
21九九乘法表
#include
int main(int argc, char const *argv[])
{
int i=0;
int j=0;
for(i=1;i<10;i++){
for(j=1;j<=i;j++){
printf("%d*%d=%d ",j,i,i*j);
}
puts("");
}
return 0;
}
22输出一个二进制：
#include
int main(int argc, char const *argv[])
{
int num;
int flag;
printf("请输入你的数字:");
scanf("%d", &num);
int i=0;
int sum[128] = {0};
while (num!=0){
flag = num % 2;
sum[i] = flag;
num/=2;
i++;
}
for (i = i-1; i>=0; i--){
printf("%d ",sum[i]);
}
puts("");
return 0;
}
23输入小写的字符，统计每个小写字符的个数：
#include
int get_index(char ch)
{
return ch - 'a';
}
int main(int argc, char const *argv[])
{
char s[128] = {0};
int i=0;
int index;
unsigned int count[32] = {0};
printf("请输入您的字符串>>");
scanf("%s", s);
while (0 != s[i]){
index = get_index(s[i]);
count[index]++;
i++;
}
for (i = 0; i<26; i++){
printf("[%c] [%d]\n",i + 'a', count[i] );
}
return 0;
}
24万年历
#include
#include
#include
int main (){
int year = 0, month = 0, day = 0;
int hour = 0, min = 0, sec = 0;
scanf("%d%d%d%d%d%d", &year, &month, &day
, &hour, &min, &sec);//输入时 以空格分隔
while(1){
system("clear");//调用clear命令清屏，实现单行显示
printf("%4d-%02d-%02d %02d:%02d:%02d\n",
year, month, day, hour, min, sec);//%02d 是格式化输出 后面讲
sec++;
if(60 == sec){
sec = 0;
min++;
if(60 == min){
min = 0;
hour++;
if(24 == hour){
hour = 0;
day++;
//31天的月
if(1 == month || 3 == month || 5 == month || 7 == month || 8 == month
|| 10 == month || 12 == month){
if(32 == day){
day = 1;
month++;
}
//30天的月
}else if(4 == month || 6 == month || 9 == month || 11 == month || 8 == month){
if(31 == day){
day = 1;
month++;
}
//闰年的2月
}else if((year%4==0 && year%100!=0) || year%400==0){
if(30 == day){
day = 1;
month++;
}
//平年的2月
}else{
if(29 == day){
day = 1;
month++;
}
}
if(13 == month){
month = 1;
year++;
}
}
}
}
sleep(1);//休眠1秒
}
return 0;
} 25比较两个字符串最长有多少个连续字符相等
#include
#include
int compare(char* arr, char* brr)
{
int i,j;
int len = 0;
int max = 0;
int temp = 0;
for (i = 0; i < strlen(arr); i = temp, i++){
temp = i;
for (j = 0, len = 0; j < strlen(brr); j++){
while (arr[i] == brr[j] && arr[i] != '\0' && brr[j] != '\0'){
len++;
i++;
j++;
max = max > len ? max : len;
}
}
}
return max;
}
int main(int argc, char const *argv[])
{
char arr[128] = "abcdefgddd";
char brr[128] = "ooooabcdefgdd";
printf("%d\n", compare(arr, brr));
return 0;
}
26统计一个字符串中不重复的字符串的最大长度：
#include
#include
#include
#include
int get_maxlen(char *s)
{
int hash[128] = {0};
int right = 0,left = 0;
int max = 0;
while(right < strlen(s)){
if (hash[s[right]] > 0){
hash[s[left]] = 0;
left++;
}else {
hash[s[right]] = 1;
right++;
max = (right - left) > max ? (right - left) : max;
}
}
return max;
}
int main(int argc, char const *argv[])
{
char arr[128] = {0};
printf("input >>");
scanf("%s", arr);
printf("%d\n", get_maxlen(arr));
return 0;
} 27打出下划线加字母
F
_FE
__FED
___FEDC
____FEDCB
_____FEDCBA#include
int main(int argc, char const *argv[])
{
int i, j, a;
char ch = 'F';
for ( i = 0; i < 6; i++){
for (j = 1; j <= i; j++){
printf("_");
}
for (a = 0, ch = 'F'; a <= i; a++){
printf("%c", ch--);
}
puts("");
}
return 0;
}
28将char类型转换为int类型
#include
int main(int argc, char const *argv[])
{
char arr[12] = "123456";
int i = 0;
int sum = 0;
while (arr[i] != 0){
sum = sum*10 + arr[i] - '0';
i++;
}
printf("%d\n", sum);
return 0;
}
29将int类型转换为char类型
#include
#include
#include
int main(int argc, char const *argv[])
{
int data = 1234567;
char str[10] = {0};
char ch[10] = {0};
int i = 0;
while (data){
str[i] = data % 10 + '0';
i++;
data = data / 10;
}
while (i){
printf("%c", str[--i]);
}
puts("");
return 0;
}
30二分查找
#include
int binary_search(int *arr, int p, int q, int ele)
{
int mid = 0;
if (p > q){
return 0;
}
mid = p + (q - p) / 2;
if (ele == arr[mid]){
return mid;
}
if (ele < arr[mid]){
return binary_search(arr, p, mid - 1, ele);
}else {
return binary_search(arr, mid + 1, q, ele);
}
}
int main(int argc, char const *argv[])
{
int arr[10] = {10, 14, 19, 26, 27, 31, 33, 35, 42, 44};
printf("%d\n", binary_search(arr, 0, 9, 31));
return 0;
}
31选择排序
#include
#include
void choose_sort(int *arr)
{
if (NULL == arr){
printf("传参错误\n");
exit(-1);
}
int i;
int j;
int max = 0;
int temp;
for (i = 0; i < 4; i++){
max = i;
for (j = i + 1; j < 5; j++){
if (arr[j] > arr[max]) max = j;
}
if (max != i){
temp = arr[max];
arr[max] = arr[i];
arr[i] = temp;
}
}
return;
}
int main(int argc, char const *argv[])
{
int arr[5] = {11, 1, 20, 2, 300};
choose_sort(arr);
for (int i = 0; i < 5; i ++){
printf("%d ", arr[i]);
}
puts("");
return 0;
}
32实现memcpy
#include
void* memcpy(void* dest, const void* src, size_t num)
{
if (NULL == dest || NULL == src){
return NULL;
}
char* pDest = (char*)dest;
char* pSrc = (char*)src;
for (int i = 0; i < num; i++){
*(pDest + i) = *(pSrc + i);
}
return dest;
}
int main(){
int arr[4] = { 4, 6, 8, 7 };
int arr2[4] = { 0 };
memcpy(arr2, arr, 16); //调用 16是字节数
for (int i = 0; i < 4; i++){ //数组循环输出
printf("%d ", arr2[i]);
}
return 0;
}
33十六进制转10进制
#include
int main(int argc, char const *argv[])
{
char a[100] = {0};
int i =0, re = 0;
printf("Enter a string:");
fgets(a, 100, stdin);
while (a[i]){
if (a[i] >= '0' && a[i] <= '9'){
re = re * 16 + a[i] - '0';
}else if(a[i] >= 'a' && a[i] <= 'f'){
re = re * 16 + a[i] + 10 -'a';
}else if(a[i] >= 'A' && a[i] <= 'F'){
re = re * 16 + a[i] + 10 - 'A';
}
i++;
}
printf("number=%d\n", re);
return 0;
}
34十进制转十六进制
#include
int main(int argc, char const *argv[])
{
char a[32] = "0123456789ABCDEF";
char b[100];
int n;
int cnt = 0;;
scanf("%d", &n);
if (n == 0){
printf("0\n");
}
while (n){
b[++cnt] = a[n % 16];
n = n / 16;
}
for (int i = cnt; i > 0; i--){
printf("%c", b[i]);
}
puts("");
return 0;
}
35将16进制的字符串，两个两个转化为16进制的数值
#include
#include
//这个函数会把字符转成，16进制的本身的值，例如 '1'->0x1 'b'-> 0xb
int sthvalue(char c)
{
int value;
if((c >= '0') && (c <= '9'))
value = 48;
else if ((c >= 'a') && (c <='f'))
value = 87;
else if ((c >= 'A') && (c <='F'))
value = 55;
else {
printf("invalid data %c",c);
return -1;
}
return value;
}
/*转化函数，把字符串和一个数组当做参数，这个函数会把str的值，每两个组合成一个16进制的数*/
int strtohex(char *str, char *data)
{
int len =0;
int sum =0;
int high=0;
int low=0;
int value=0;
int j=0;
len = strlen(str);//获取字符串的字符个数
//char data[256] = {0};
printf("%d\n", len);
//在for循环中，从0开始，每两个数组成一个16进制，高4位和低4位，然后放技能数组中去
for(int i=0; i 36时间戳和标准时间直接的相互转换
#include
#include
#include
#include
/*标准时间转换为时间戳*/
int standard_to_stamp(char *str_time)
{
struct tm stm;
int iY,iM,iD,iH,iMin,iS;
int i;
memset(&stm,0,sizeof(stm));
int arr[5] = {4, 7, 10, 13, 16};
//Check whether the entered time format is correct
if (strlen(str_time) != TIME_LEN){
printf("The entered time format is incorrect\n"
"Please enter in the correct format for example: 2023-02-03 13:54:00\n");
exit(EXIT_FAILURE);
}
for (i = 0; i < strlen(str_time); i++){
if (str_time[i] < '0' || str_time[i] > '9'){
if (!(i == arr[0] || i == arr[1] || i == arr[2] || i == arr[3] || i== arr[4])){
printf("The entered time format is incorrect\n"
"Please enter in the correct format for example: 2023-02-03 13:54:00\n");
exit(EXIT_FAILURE);
}
}
if (i < 5){
if (!((str_time[arr[i]] == ' ') || (str_time[arr[i]] == '.') || (str_time[arr[i]] == '-') || (str_time[arr[i]] == ':'))){
printf("The entered time format is incorrect\n"
"Please enter in the correct format for example: 2023-02-03 13:54:00\n");
exit(EXIT_FAILURE);
}
}
}
iY = atoi(str_time);
iM = atoi(str_time+5);
iD = atoi(str_time+8);
iH = atoi(str_time+11);
iMin = atoi(str_time+14);
iS = atoi(str_time+17);
if ((iY < 1900)){
printf("The input year cannot be less than 1900\n");
exit(EXIT_FAILURE);
}
if ((iM < 1) || (iM > 12)){
printf("The value ranges from 1 to 12 months\n");
exit(EXIT_FAILURE);
}
switch(iM)
{
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
if(iD<1 || iD>31) {
printf("Each month of 1, 3, 5, 7, 8, 10, 12 has 31 days\n");
exit(EXIT_FAILURE);
}
break;
case 4: case 6: case 9: case 11:
if(iD<1 || iD>30) {
printf("Each month of 4, 6, 9, 11 has 30 days\n");
exit(EXIT_FAILURE);
}
break;
case 2:
if((iY % 4 ==0 && iY % 100 !=0) || iY % 400 ==0) {
if(iD<1 || iD>29){
printf("February should have 29 days if it is a leap year\n");
exit(EXIT_FAILURE);
}
}else{
if(iD<1 || iD>28) {
printf("February would have 28 days in a normal year\n");
exit(EXIT_FAILURE);
}
}
break;
}
if (iH > 24 || iH < 0){
printf("Hours range from 0 to 24\n");
exit(EXIT_FAILURE);
}
if (iMin < 0 || iMin > 59){
printf("The value ranges from 0 to 59 minutes\n");
exit(EXIT_FAILURE);
}
if (iS < 0 || iS > 59){
printf("The value ranges from 0 to 59 seconds\n");
exit(EXIT_FAILURE);
}
stm.tm_year=iY-1900;
stm.tm_mon=iM-1;
stm.tm_mday=iD;
stm.tm_hour=iH;
stm.tm_min=iMin;
stm.tm_sec=iS;
return (int)mktime(&stm);
}
/*时间戳转换为标准时间*/
typedef struct times
{
int Year;
int Mon;
int Day;
int Hour;
int Min;
int Second;
}Times;
Times stamp_to_standard(int stampTime)
{
time_t tick = (time_t)stampTime;
struct tm tm;
char s[100];
Times standard;
tm = *localtime(&tick);
strftime(s, sizeof(s), "%Y-%m-%d %H:%M:%S", &tm);
printf("时间戳为：%d 转换成标准时间为： %s\n", (int)tick, s);
standard.Year = atoi(s);
standard.Mon = atoi(s+5);
standard.Day = atoi(s+8);
standard.Hour = atoi(s+11);
standard.Min = atoi(s+14);
standard.Second = atoi(s+17);
return standard;
}
int main(int argc, char **argv)
{
int a =0;
printf("输入的标准时间是: %s \n",argv[1]);
a=standard_to_stamp(argv[1]);
printf("标准时间转换为时间戳: %d\n",a);
stamp_to_standard(a);
return 0;
}
37将10进制数转换为16进制的字符
char buffer [33];
char * inttohex( int aa)
{
static int i = 0;
if (aa < 16)
{
if (aa < 10)
buffer[i] = aa + '0' ;
else
buffer[i] = aa - 10 + 'A' ;
buffer[i+1] = '\0' ;
}
else
{
inttohex(aa / 16);
i++;
aa %= 16;
if (aa < 10)
buffer[i] = aa + '0' ;
else
buffer[i] = aa - 10 + 'A' ;
}
return (buffer);
}38判断你输入的是否是mac地址
#include
#include
int main() {
regex_t regex;
int reti;
char ip[] = "11:ff:22:ff:ff:ff";
reti = regcomp(®ex, "^([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}$", REG_EXTENDED);
if (reti) {
char error_msg[100];
regerror(reti, ®ex, error_msg, sizeof(error_msg));
fprintf(stderr, "Could not compile regex: %s\n", error_msg);
return 1;
}
reti = regexec(®ex, ip, 0, NULL, 0);
if (!reti) {
printf("Match\n");
} else if (reti == REG_NOMATCH) {
printf("No match\n");
} else {
char error_msg[100];
regerror(reti, ®ex, error_msg, sizeof(error_msg));
fprintf(stderr, "Regex match failed: %s\n", error_msg);
return 1;
}
regfree(®ex);
return 0;
}
39判断你输入的是否是一个正确的ip地址
#include
#include
int isValidIpAddress(char* ipAddress) {
regex_t regex;
int reti;
// 编译正则表达式
reti = regcomp(®ex, "^([0-9]{1,3}\\.){3}[0-9]{1,3}$", 1);
if(reti) {
fprintf(stderr, "Could not compile regex.\n");
return -1;
}
// 匹配正则表达式
reti = regexec(®ex, ipAddress, 0, NULL, 0);
// 释放正则表达式
regfree(®ex);
if(!reti) {
return 1;
}
else {
return 0;
}
}
int main() {
char ipAddress[] = "192.168.1.1";
int isValid = isValidIpAddress(ipAddress);
if(isValid) {
printf("%s is a valid IP address.\n", ipAddress);
}
else {
printf("%s is not a valid IP address.\n", ipAddress);
}
return 0;
}
40 getopt_long的使用方法
#include
#include
#include
int main(int argc, char *argv[]) {
int opt;
int option_index = 0;
struct option long_options[] = {
{"help", no_argument, 0, 'h'},
{"version", no_argument, 0, 'v'},
{"output", required_argument, 0, 'o'},
{"input", required_argument, 0, 'i'},
{0, 0, 0, 0} // 最后一项是必需的，用于指示选项数组结束
};
while ((opt = getopt_long(argc, argv, "hvo:i:", long_options, &option_index)) != -1) {
switch (opt) {
case 'h':
printf("帮助信息：...\n");
break;
case 'v':
printf("版本信息：...\n");
break;
case 'o':
printf("输出文件：%s\n", optarg);
break;
case 'i':
printf("输入文件：%s\n", optarg);
break;
case '?':
// 当出现不认识的选项或缺少必要的参数时，会返回 '?'，并输出错误信息到 stderr
fprintf(stderr, "无效的选项或缺少参数：%c\n", optopt);
break;
default:
// 如果使用了没有在选项数组中定义的选项，则会执行 default 分支
fprintf(stderr, "未处理的选项：%c\n", opt);
break;
}
}
// 处理剩余的非选项参数（不带'-'或'--'的参数）
for (int i = optind; i < argc; i++) {
printf("非选项参数：%s\n", argv[i]);
}
return 0;
} 41 判断从终端输入的密码是否正确
#include
#include
#include
#include
int main(int argc, char* argv[])
{
char buf[1024] = {0};
struct termios old_term, new_term;
int count = 0;
int j = 0;
char ch = 0;
tcgetattr(STDIN_FILENO, &old_term);
new_term = old_term;
new_term.c_lflag &= ~(ICANON | ECHO);
tcsetattr(STDIN_FILENO, TCSANOW, &new_term);
memset(buf, 0, 1024);
printf("Password:");
while(1) {
ch = getchar();
if (ch == '\n') {
if (!strcmp(buf, "asd"))
break;
else {
memset(buf, 0, 1024);
j = 0;
printf("\nerror password.\n");
}
printf("Password:");
++count;
if (count >= 3)
return 0;
}else {
buf[j++] = ch;
if (j >= 1024) {
memset(buf, 0, 1024);
j = 0;
printf("\nerror Invalid password.\n");
printf("Password:");
}
}
}
tcsetattr(STDIN_FILENO, TCSANOW, &old_term);
printf("\n");
} 42 生成一个1-100之间的随机数
#include
#include
#include
int main() {
int min_value = 1; // 随机数的最小值
int max_value = 100; // 随机数的最大值
// 使用当前时间作为随机数种子
srand(time(NULL));
// 生成一个介于min_value和max_value之间的随机数
int random_number = min_value + rand() % (max_value - min_value + 1);
printf("随机数: %d\n", random_number);
return 0;