#include <stdio.h>
void copy_string(char *from, char *to)
{

        for( ; *from != '\0'; from ++, to ++ )
        {
            
                *to = *from;
               
        }
        *to = '\0';

}

int main()
{

        char *a = "I am a teacher";
        char *b = "You are a student";
        //copy_string(*a, *b);
        copy_string(a, b);
        //puts(*b);
        puts(b);
        return 0;

}

所谓的字符串常量不可修改

可以把字符串常量存储在一个字符数组中:
char a[50]="......."
char b[50]="......."
这样就可以修改了

[ 本帖最后由 cheetah 于 2013-7-30 07:23 编辑 ]

char *a = "I am a teacher";
char *b = "You are a student";
字符串"I am a teacher"存在只读区，指针a指向该只读区，copy_string（）函数试图对该只读区修改 ，就出现段错误