ASCII值与字符相互转换程序

#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>
/**chartoasc:char -> ascii**/
int chartoasc(char c)
{
    int i=0;
    i = c;
    return i;
}
/**asctochar:ascii -> char**/
char asctochar(int a)
{
    char c;
    c = a;
    return c;
}
int main(int argc,char *argv[])
{

    if(argc!=3)
    {
        printf("usage:a.out flag char\nflag=1:chartoasc\nflag=2:asctochar\n");
        return -1;
    }
    int flag=0;
    flag = atoi(argv[1]);
    char c ;
    char *p;
    int a ;
    if(flag==1)
    {
        p = argv[2];
        c = *p;
        printf("输入的字符：%c\n",c);
        a = chartoasc(c);
        printf("%c的ascii值是:%d\n",c,a);
    }
    if(flag==2)
    {
        a = atoi(argv[2]);
        printf("输入的ascii值是：%d\n",a);
        c = asctochar(a);
        printf("%d的字符形式是:%c\n",a,c);
    }
    return 0;

}