#include<math.h>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define pi 3.1415926
    void main(int argc,char *argv[])
    {
         void printtan();
         void printsin(); char *tan='-t',*sin='-s'; clrscr();
         if(argc!=2){printf("wrong!");exit(0);}
         if(strcmp(argv[1],tan)==0)
         printtan();
        else if(strcmp(argv[1],sin)==0)
         printsin();
         else printf("error");

    }
    void printtan()
    { int i;
      printf("tan 0=0\n");
      for(i=100;i>=1;i++)
      { if(i%3==0)
        printf("\n");
        printf("tan%f=%f",2*pi/i,tan(2*pi/i));
      }
    }
    void printsin()
    { int i;
      printf("sin 0=0\n");
      for(i=100;i>=1;i++)
      { if(i%5==0)
        printf("\n");
        printf("sin%f=%f",2*pi/i,sin(2*pi/i));
      }
    }

当没有输入参数时，只是输出程序名时，总是输出正切函数表