代码 1 随机数函数,太坑了,怎么是个固定的数?
/* Magic number program #1. */
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int magic; /* magic number */
int guess; /* user's guess */
magic = rand(); /* generate the magic number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if(guess == magic)
printf("** Right **");
return 0;
}
代码 2 同上
/* Magic number program #2. */
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int magic; /* magic number */
int guess; /* user's guess */
magic = rand(); /* generate the magic number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if(guess == magic)
printf("** Right **");
else
printf("Wrong");
return 0;
}
代码 3 条件语句嵌套
if(i)
{
if(j) statement 1;
if(k)
statement 2; /* this if */
else
statement 3; /* is associated with this else */
}
else
statement 4; /* associated with if(i) */
代码 4
/* Magic number program #3. */
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int magic; /* magic number */
int guess; /* user's guess */
magic = rand(); /* get a random number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if (guess == magic)
{
printf("** Right **");
printf(" %d is the magic number\n", magic);
}
else
{
printf("Wrong, ");
if(guess > magic)
printf("too high\n"); /* nested if */
else
printf("too low\n");
}
return 0;
}
代码 5 if elseif else
/* Magic number program #4. */
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int magic; /* magic number */
int guess; /* user's guess */
magic = rand(); /* generate the magic number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if(guess == magic) {
printf("** Right ** ");
printf("%d is the magic number", magic);
}
else if(guess > magic)
printf("Wrong, too high");
else
printf("Wrong, too low");
return 0;
}
代码 6 三元运算,等价于 代码 7
x = 10;
y = x>9 ? 100 : 200;
代码 7
x = 10;
if(x>9)
y = 100;
else
y = 200;
代码 8
#include <stdio.h>
int main(void)
{
int isqrd, i;
printf("Enter a number: ");
scanf("%d", &i);
isqrd = i>0 ? i*i : -(i*i);
printf("%d squared is %d", i, isqrd);
return 0;
}
代码 9
#include <stdio.h>
int f1(int n);
int f2(void);
int main(void)
{
int t;
printf("Enter a number: ");
scanf("%d", &t);
/* print proper message */
t ? f1(t) + f2() : printf("zero entered.");
printf("\n");
return 0;
}
int f1(int n)
{
printf("%d ", n);
return 0;
}
int f2(void)
{
printf("entered ");
return 0;
}
代码 10
/* Magic number program #5. */
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int magic;
int guess;
magic = rand(); /* generate the magic number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if(guess == magic)
{
printf("** Right ** ");
printf("%d is the magic number", magic);
}
else
guess > magic ? printf("High") : printf("Low");
return 0;
}
代码 11
/* Divide the first number by the second. */
#include <stdio.h>
int main(void)
{
int a, b;
printf("Enter two numbers: ");
scanf("%d%d", &a, &b);
if(b)
printf("%d\n", a/b);
else
printf("Cannot divide by zero.\n");
return 0;
}
代码 12
if(b != 0)
printf("%d\n", a/b);
代码 13 switch void menu(void)
{
char ch;
printf("1. Check Spelling\n");
printf("2. Correct Spelling Errors\n");
printf("3. Display Spelling Errors\n");
printf("Strike Any Other Key to Skip\n");
printf(" Enter your choice: ");
ch = getchar(); /* read the selection from the keyboard */
switch(ch) {
case '1':
check_spelling();
break;
case '2':
correct_errors();
break;
case '3':
display_errors();
break;
default :
printf("No option selected");
}
}
代码 14
/* Process a value */
void inp_handler(int i)
{
int flag;
flag = -1;
switch(i) {
case 1: /* These cases have common */
case 2: /* statement sequences. */
case 3:
flag = 0;
break;
case 4:
flag = 1;
case 5:
error(flag);
break;
default:
process(i);
}
}
代码 15
flag = 0;
break;
代码 16
switch(x) {
case 1:
switch(y) {
case 0: printf("Divide by zero error.\n");
break;
case 1: process(x,y);
break;
}
break;
case 2:
.
.
.
代码 17
#include <stdio.h>
int main(void)
{
int x;
for(x=1; x <= 100; x++) printf("%d ", x);
return 0;
}
代码 18
for(x=100; x != 65; x -= 5) {
z = x*x;
printf("The square of %d, %f", x, z);
}
代码 19
x = 10;
for(y=10; y!=x; ++y)
printf("%d", y);
printf("%d", y); /* this is the only printf() statement that will execute */
代码 20
for(x=0, y=0; x+y<10; ++x) {
y = getchar();
y = y - '0'; /* subtract the ASCII code for 0 from y */
.
.
.
}
代码 21
/* Demonstrate multiple loop control variables. */
#include <stdio.h>
#include <string.h>
void converge(char *targ, char *src);
int main(void)
{
char target[80] = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
converge(target, "This is a test of converge().");
printf("Final string: %s\n", target);
return 0;
}
/* This function copies one string into another. It copies characters to both the ends,converging at the middle. */
void converge(char *targ, char *src)
{
int i, j;
printf("%s\n", targ);
for(i=0, j=strlen(src); i<=j; i++, j--)
{
targ[i] = src[i];
targ[j] = src[j];
printf("%s\n", targ);
}
}
代码 22
void sign_on(void)
{
char str[20];
int x;
for(x=0; x<3 && strcmp(str, "password"); ++x)
{
printf("Enter password please:");
gets(str);
}
if(x==3) return;
/* else log user in ... */
}
代码 23
#include <stdio.h>
int sqrnum(int num);
int readnum(void);
int prompt(void);
int main(void)
{
int t;
for(prompt(); t=readnum(); prompt())
sqrnum(t);
return 0;
}
int prompt(void)
{
printf("Enter a number: ");
return 0;
}
int readnum(void)
{
int t;
scanf("%d", &t);
return t;
}
int sqrnum(int num)
{
printf("%d\n", num*num);
return num*num;
}
代码 24
for(x=0; x!=123; )
scanf("%d", &x);
代码 25
gets(s); /* read a string into s */
if(*s)
x = strlen(s); /* get the string's length */
else
x = 10;
for( ; x<10; )
{
printf("%d", x);
++x;
}
代码 26
for( ; ; )
printf("This loop will run forever.\n");
代码 27
ch = '\0';
for( ; ; ) {
ch = getchar(); /* get a character */
if(ch=='A')
break; /* exit the loop */
}
printf("you typed an A");
代码 28
for( ; *str == ' '; str++) ;
代码 29
for(t=0; t<SOME_VALUE; t++) ;
代码 30
/*
Here, i is local to for loop; j is known outside loop.
*** This example is invalid for C89. ***
*/
int j;
for(int i = 0; i<10; i++)
j = i * i;
/* i = 10; *** Error *** -- i not known here! */
代码 31
char wait_for_char(void)
{
char ch;
ch = '\0'; /* initialize ch */
while(ch != 'A') ch = getchar();
return ch;
}
代码 32
#include <stdio.h>
#include <string.h>
void pad(char *s, int length);
int main(void)
{
char str[80];
strcpy(str, "this is a test");
pad(str, 40);
printf("%d", strlen(str));
return 0;
}
/* Add spaces to the end of a string. */
void pad(char *s, int length)
{
int l;
l = strlen(s); /* find out how long it is */
while(l<length)
{
s[l] = ' '; /* insert a space */
l++;
}
s[l]= '\0'; /* strings need to be terminated in a null */
}
代码 33 void func1(void)
{
int working;
working = 1; /* i.e., true */
while(working)
{
working = process1();
if(working)
working = process2();
if(working)
working = process3();
}
}
代码 34 while
while((ch=getchar()) != 'A') ;
代码 35 do while do {
scanf("%d", &num);
} while(num > 100);
代码 36 do while
void menu(void)
{
char ch;
printf("1. Check Spelling\n");
printf("2. Correct Spelling Errors\n");
printf("3. Display Spelling Errors\n");
printf(" Enter your choice: ");
do {
ch = getchar(); /* read the selection from
the keyboard */
switch(ch) {
case '1':
check_spelling();
break;
case '2':
correct_errors();
break;
case '3':
display_errors();
break;
}
} while(ch!='1' && ch!='2' && ch!='3');
}
代码 37 goto
x = 1;
loop1:
x++;
if(x<=100)
goto loop1;
代码 38 #include <stdio.h>
int main(void)
{
int t;
for(t=0; t<100; t++)
{
printf("%d ", t);
if(t==10) break;
}
return 0;
}
代码 39
void look_up(char *name)
{
do {
/* look up names ... */
if(kbhit()) break;
} while(!found);
/* process match */
}
代码 40
for(t=0; t<100; ++t) {
count = 1;
for(;;) {
printf("%d ", count);
count++;
if(count==10) break;
}
}
代码 41
#include <stdlib.h>
int main(void)
{
if(!virtual_graphics()) exit(1);
play();
/* ... */
}
/* .... */
代码 42
void menu(void)
{
char ch;
printf("1. Check Spelling\n");
printf("2. Correct Spelling Errors\n");
printf("3. Display Spelling Errors\n");
printf("4. Quit\n");
printf(" Enter your choice: ");
do {
ch = getchar(); /* read the selection from the keyboard */
switch(ch) {
case '1':
check_spelling();
break;
case '2':
correct_errors();
break;
case '3':
display_errors();
break;
case '4':
exit(0); /* return to OS */
}
} while(ch!='1' && ch!='2' && ch!='3');
}
代码 43
/* Count spaces */
#include <stdio.h>
int main(void)
{
char s[80], *str;
int space;
printf("Enter a string: ");
gets(s);
str = s;
for(space=0; *str; str++)
{
if(*str != ' ') continue;
space++;
}
printf("%d spaces\n", space);
return 0;
}
代码 44
void code(void)
{
char done, ch;
done = 0;
while(!done) {
ch = getchar();
if(ch=='$') {
done = 1;
continue;
}
putchar(ch+1); /* shift the alphabet one position higher */
}
}
代码 45
func(); /* a function call */
a = b+c; /* an assignment statement */
b+f(); /* a valid, but strange statement */
; /* an empty statement */
代码 46
#include <stdio.h>
int main(void)
{
int i;
{ /* a free-standing block statement */
i = 120;
printf("%d", i);
}
return 0;
}
