C语言getopt函数

C语言的getopt()函数用于分析命令行参数。它的声明为：
int getopt(int argc, char * const argv[], const char * optstring);
该函数通过解析命令行参数来获取选项和参数的值。用户可以在命令行中使用不同的选项来传递参数给程序。

下面是一个getopt()函数的示例代码：
#include <unistd.h>
#include <stdio.h>
int main(int argc, char * argv[]){
int i;
printf("%s\n","argv原序：");
for(i = 0;i < argc;i++){
printf("%s ",argv[i]);
}
printf("\n");
printf("START@optind:%d，opterr：%d\n",optind,opterr);
int ret;
while((ret = getopt(argc,argv,"aW;b:c:de::")) != -1){
switch(ret){
case 'a': printf("Having option -a\n"); break;
case 'b': printf("having option -b,and its argument is %s\n",optarg); break;
case 'c': printf("having option -c,and its argument is %s\n",optarg); break;
case 'd': printf("Having option -d\n"); break;
case 'e': printf("having option -e,it is optional,and its argument is %s\n",optarg); break;
case '?': printf("Unknown option -%c\n",(char)optopt); break;
}
}
printf("END@optind:%d，argv[%d]：%s\n",optind,optind,argv[optind]);
printf("%s\n","argv现序：");
for(i = 0;i < argc;i++){
printf("%s ",argv[i]);
}
printf("\n");
return 0;
}

该示例演示了如何使用getopt()函数解析命令行参数。程序通过指定选项和参数的形式来接受用户输入，并根据不同的选项执行不同的操作。在示例中，选项包括：a、b、c、d和e，其中e选项是可选的。通过在命令行中输入相应的选项和参数，程序会根据不同的选项执行相应的代码逻辑。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
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