int main(int argc,char *argv[])用法问题怎么让argc=2啊

#include
#include
int main(int argc,char *argv[])
{
int ch;
FILE *fp;
long cout=0;
if(argc!=2)
{
printf("Usage :%s filename\n",argv[0]);
exit(1);
}
if((fp=fopen(argv[1],"a"))==NULL)
{
printf("can't open %s",argv[1]);
exit(1);
}
while(ch==getc(fp)!=EOF)
{
putc(ch,stdout);
cout++;
}
fclose(fp);
printf("file %s has %ld characters\n",argv[1],cout);
return 0;

}
这个怎么让argc不等于1 我用的vs 谢谢