Lunix环境下用main函数的参数实现一个简易参数

#include<stdio.h>int sub(int a,int b){return a-b;}int mydiv(int a,int b){if(0==b){printf("the divsor is zero!\n");return -1;}return a/b;}int add(int a,int b){return a+b;}int multi(int a,int b){return a*b;}void usage(const char*proc){printf("Usage:%s-[a|s|d] data1,data2",proc);}int main(int argc,char *argv[]){int data1=atoi(argv[2]);int data2=atoi(argv[3]); if(argc!=4)  {    usage(argv[0]);   return 1;  }if(strcmp("-a",argv[1])==0) {printf("res:%d\n",add(data1,data2)); }else if(strcmp("-s",argv[1])==0) {printf("res:%d\n",sub(data1,data2)); }else if(strcmp("-m",argv[1])==0){printf("res: %d\n",multi(data1,data2));}else if(strcmp("-d",argv[1])==0) {if(mydiv(data1,data2)!=-1){printf("res:%d\n",mydiv(data1,data2));}else{return -1;}}else{usage(argv[0]);}return 0；}