巩固C语言(五)----获取CMD输出的字符串 & 字符串的拷贝、查找、长度 & 实例之调戏QQ

1 获取CMD中字符串的输出：

#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>#include<stdlib.h>#include<string.h>void getCMD(char *in, char *out){char buffer[128] = { 0 };FILE *pipe = _popen(in, "r");//获取命令行的输入,并执行，pipe相当于一个管道if (!pipe)exit(-1);while (!feof(pipe))//判断文件是否结束{if (fgets(buffer, 128, pipe))//从管道中读取数据{strcat(out, buffer);}}_pclose(pipe);//关闭该管道}void main(){FILE *my_out = fopen("out.txt", "w");if (!my_out)exit(-1);char CMDin[50] = { 0 };char CMDout[4096] = { 0 };scanf("%s", CMDin);getCMD(CMDin, CMDout);printf("打印输出：%s", CMDout);printf("\nstrlen(CMDout) = %d\n", strlen(CMDout));fprintf(my_out, "%s", CMDout);fclose(my_out);system("pause");}

在out.txt中将会出现和CMD中一样的输出字符串。

2 与文件相关的指令

C语言程序在进行文件操作时遵循如下操作步骤：打开读写操作关闭，通俗地说，打开是获取文件结构、系统为文件分配缓冲区的过程，不打开文件就不能对其进行读写，关闭是释放缓冲区和其他资源的过程，不关闭文件就会慢慢耗光系统资源，。在进行文件操作时，系统自动与3个标准设备文件联系，这3个文件无需打开和关闭，它们的文件指针分别是：stdin：标准输入文件指针，系统分配为键盘。stdout：标准输出文件指针，系统分配为显示器。stderr：标准错误输出文件指针，系统分配为显示器。举例来说，从文件输入和向文件输出有两个对应函数fscanf和fprintf，两个函数的原型分别为：int fprintf(FILE* ofp,控制字符串，参数表);int fscanf(FILE* ifp ,控制字符串，参数表);参数表中参数的个数同样是任意的，fprintf函数用于将转换后的控制字符串写出到ofp指向的文件中，fscanf用于从ifp指向的文件中读取字节信息为参数表中的参数赋值。前面章节中用到的标准输入输出函数printf和scanf实际上等价于：fprintf(stdout, 控制字符串，参数表)fscanf(stdin, 控制字符串，参数表)

3 字符串的拷贝、查找、长度

#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>#include<stdlib.h>int strLength(const char *str){int num = 0;while (*str){num++;str++;}return num;}void  strCat(char *dest, const char *sour){//注意当 char *dest = "Apple Lin"时会发生错误，因为不知道dest最多能承载多少字符//当然遇到这种情况时可以用realloc函数实现int destLen = strLength(dest);int sourLen = strLength(sour);char *temp = dest + destLen;while (*sour){*temp = *sour;temp++;sour++;}*temp = '\0';}char * StrStr(char *sour, char *find){char *p = NULL;//要返回的地址指针int sourLen = strLength(sour);int findLen = strLength(find);for (int i = 0; i < sourLen - findLen; i++){int flag = 1;//标识符for (int j = 0; j < findLen; j++){if (sour[i + j] != find[j]){flag = 0;break;}}if (flag == 1)//找到了{p = &sour[i];break;}}return p;}void main(){char str[40] = "Apple Lin";char sour[20] = " Qian Qin";printf("length = %d\n", strLength(str));strCat(str, sour);printf("*str = %s\n", str);printf("length = %d\n", strLength(str));char find[10] = "Lin";char *p = StrStr(str, find);if (p == NULL)printf("Not find!\n");elseprintf("Find!\n");system("pause");}

运行结果：

length = 9*str = Apple Lin Qian Qinlength = 18Find!请按任意键继续. . .

4 调戏QQ----找到QQ并将之关闭

#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>#include<stdlib.h>#include<string.h>int strLength(const char *ch){int num = 0;while (*ch){num += 1;ch++;}return num;}void strCat(char *dest, const char *sour){int destLen = strLength(dest);int sourLen = strLength(sour);char *temp = dest + destLen;while (*sour){*temp = *sour;temp++;sour++;}*temp = '\0';}//需要使用下标char * strFind(char *dest, char *str){char *p = NULL;int destLen = strLength(dest);int strLen = strLength(str);for (int i = 0; i < destLen - strLen; i++){int flag = 1;for (int j = 0; j < strLen; j++){if (dest[i + j] != str[i]){flag = 0;break;}}if (flag == 1){p = dest + i;break;}}return p;}//不需要使用下标char * strFind2(char *dest, char *str){char *p = NULL;for (char *tem_dest = dest; *tem_dest != '\0'; tem_dest++){int flag = 1;for (char *tem_str = str; *tem_str != '\0'; tem_str++){if (*(tem_dest + (tem_str - str)) == '\0'){flag = 0;break;}if (*(tem_dest + (tem_str - str)) != *tem_str){flag = 0;break;}}if (flag == 1){p = tem_dest;break;}}return p;}void receCMD(char *cmd, char *out){FILE *pipe = _popen(cmd, "r");char buffer[128] = { 0 };if (!pipe)exit(-1);while (!feof(pipe)){if(fgets(buffer, 128, pipe))strCat(out, buffer);}_pclose(pipe);}void main(){char in[40] = "tasklist";char out[9192] = { 0 };/*printf("请您输入指令：");scanf("%s", in);*/receCMD(in, out);char *p = strFind2(out, "QQ.exe");if (p){printf("QQ存在,关闭之...!");system("taskkill /f /im QQ.exe");}elseprintf("QQ不存在!");system("pause");}