CH1 绪论
(5) 外部变量、头文件、多个文件
//File: extvar.h
#ifndef _EXTVAR_H
#define _EXTVAR_H
#ifdef __cplusplus
extern "C" {
#endif
#define MAXLINE 1000
int Max = 0;
char LongestLine[MAXLINE] = "";
#ifdef __cplusplus
}
#endif
#endif /* _EXTVAR_H */
//getLine.c
#include<stdio.h>
int getLine( char tmpStr[]){
int ch, i = 0;
while((ch = getchar()) != EOF && ch != '\n'){
tmpStr[i++] = ch;
}
tmpStr[i] = '\0';
return i;
}
//copy.c
void copy( char target[], const char source[]){
int i;
for(i = 0; source[i] != '\0'; i++){
target[i] = source[i];
}
target[i] = '\0';
}
#include <stdio.h>
#include <stdlib.h>
#include "extvar.h"
/*
注意：程序中，MAXLINE，Max，LongestLine定义在extvar.h中
*/
int main( int argc, char** argv) {
char tmpStr[MAXLINE];
int length;
while((length = getLine(tmpStr)) > 0){ //调用getLine函数
if(length > Max){
Max = length;
copy(LongestLine,tmpStr); //调用copy函数
}
}
printf( "The Max Length is: %d\n", Max);
printf( "%s\n", LongestLine);
return (EXIT_SUCCESS);
}
(4)字符数组：求最长的行
#include<stdio.h>
#include<stdlib.h>
#define MAX 1000
/*
字符串拷贝
*/
void copy( char target[], const char source[]){ //从source拷贝到target字符数组
int i = 0;
while(source[i] != '\0')
target[i] = source[i++]; //i++ 自增，向后挪
target[i] = '\0'; //在target字符串的末尾加上'\0'
}
/*
获取最长行，并返回其长度
*/
int getLongestLine( char longestLine[]){ //用字符数组做参数，实质上传地址
char tmpLine[MAX];
char ch;
int maxLength, i;
maxLength = i = 0;
while((ch = getchar()) != EOF){
if(ch != '\n') tmpLine[i++] = ch;
else {
tmpLine[i] = '\0';
if(maxLength < i){ //是否出现了新的最长行
maxLength = i;
copy(longestLine, tmpLine); //copy的定义在前，调用在后
}
i = 0; //让tmpLine行重新回到行首
}
}
return maxLength;
}
int main( int args, char** argv){
char longestLine[MAX];
printf( "Please input several lines end with Ctrl+D:\n");
int length = getLongestLine(longestLine); //数组名作参数，传地址
printf( "length = %d, line = %s\n", length, longestLine);
return EXIT_SUCCESS;
}
(3)用数组统计每个'0'~'9'之间每个字符出现的个数
/*
用数组统计每个'0'~'9'之间每个字符出现的个数
* 而不是用10个变量来记忆
*/
#include<stdio.h>
#include<stdlib.h>
int main( int argc, char** argv){
int ch, i, nwhite, nother;
char ndigit[10];
nwhite = nother = 0;
for(i = 0; i < 10; i++)
ndigit[i] = 0;
while((ch = getchar()) != EOF){
if(ch <= '9' && ch >= '0') //判断ch是否满足'0'<ch<'9'
ndigit[ch-'0']++; //正好可以定位到ch[x]的下标
else if(ch == ' ' || ch == '\t' || ch == '\n')
nwhite++;
else
nother++;
}
for(i = 0; i < 10; i++)
printf( "%d's num is: %d\n", i, ndigit[i]);
printf( "number of white is: %d\n", nwhite);
printf( "number of other is: %d\n", nother);
return EXIT_SUCCESS;
}
(2) 字符输入输出及分析统计
#include <stdio.h>
#include <stdlib.h>
#define OUT 0
#define IN 1
/*
计数空格、tab、行、字的数目
*/
void count(){
long nch;
int nblanks, ntabs, nlines, nwords, ch; //声明
int state;
nch = 0;
nblanks = ntabs = nlines = nwords = 0; //连续赋初值，从右向左
state = OUT;
printf( "\nWorld Counting");
printf( "\nPlease input a paragraph with several lines end with Ctrl+D:\n");
while((ch = getchar()) != EOF){
++nch;
if(ch == ' ') nblanks++;
else if(ch == '\t') ntabs++;
else if(ch == '\n') nlines++;
//统计字
if(ch == ' ' || ch == '\t' || ch == '\n') // ||或，从左到右
state = OUT;
else if(state != IN){
state = IN;
++nwords;
}
}
printf( "\nnch =%ld, nblanks = %d, ntabs = %d, nlines = %d, nwords = %d\n",
nch, nblanks, ntabs, nlines, nwords); //%ld表示长整形
}
/*
获取输入，去掉多余的空格，然后输出
*/
void removeBlank21(){
int ch, nblank;
nblank = 0;
while((ch = getchar()) != EOF){
if(ch != ' ') {
putchar(ch);
nblank = 0;
} else if(nblank == 0) {
putchar(ch);
nblank++;
}
}
}
/*
每行打印一个word
*/
void wordPerLine(){
printf( "\nPlease input several strings end with Ctrl+d\n");
int ch;
while((ch = getchar()) != EOF){
if(ch == ' ' || ch == '\t')
putchar('\n');
else putchar(ch);
}
}
int main( int argc, char** argv) {
//count();
//removeBlank21();
//wordPerLine();
printf( "\n%d\t%d\n",'A','\n'); //打印字符'A'(65)和'\n'(10)的ASCII码
return (EXIT_SUCCESS);
}
#include <stdio.h>
#include <stdlib.h>
#define LOWER 0 //符号常量
#define UPPER 300
#define STEP 20
int main( int argc, char** argv) {
int ftemp;
float ctemp;
/* //注释
int lower, upper, step;
lower = 0;
upper = 300;
step = 20;
*/
printf( "================================\n");
ftemp = LOWER;
while(ftemp <= UPPER){ // /除符号，注意整除与float除
ctemp = 5 * (ftemp - 32) / 9.0; //int 转换为 float
printf( "%3d\t%5.2f\n", ftemp, ctemp); //%3d宽度为3，右对齐
ftemp = ftemp + STEP;
}
printf( "================================\n");
for(ftemp = LOWER; ftemp <= UPPER; ftemp += STEP){
ctemp = 5 * (ftemp - 32) / 9.0; //
printf( "%3d\t%6.1f\n", ftemp, ctemp); //%6.1f宽度为6，小数点后一位有效数字
}
printf( "================================\n");
for(ftemp = LOWER; ftemp <= UPPER; ftemp += STEP)
printf( "%5d %6.2f\n", ftemp, (5.0/9)*(ftemp-32)); //表达式也可以错printf参数
printf( "================================\n");
return (EXIT_SUCCESS);
}