如何编写C程序使用linux命令行替换字符

Question

我对这个系统编程很新，我知道系统调用，但我没有得到的是如何编写程序来在文本中第一次出现交换字符。希望有人可以帮助我真正挣扎

Answer 1

void main()
{
    char a[20],b;
    char *ptr;
    clrscr();
    printf("\n Please Give The STRING OF A : ");
    scanf("%s",a);
    flushall();
    printf("\n Please Give The CHARACTER TO B : ");
    scanf("%c",&b);

ptr = strchr(a, b);

if (ptr)
   printf("The character %c is at position: %d\n", b, ptr-a+1);
else
   printf("The character was not found\n");
getch();

}