拷贝字符串

   看了练习的题目，要求实现strccpy库函数，这样实现了一下：
[root@bjxdurs235 c-study]# vi copy_n_str.c

#include
void copy_n( char dst[], char src[], int n){
        int i,dst_len,src_len;
        dst_len = strlen(dst);
        src_len = strlen(src);
        if (n > dst_len || n < 0){
                printf("input error ! \n dst[] can not store %d chars\n",n);
                return ;
        }

        if( n > src_len)
                n = src_len;

        for (i=0; i                dst[i] = src[i];

        }

        if (i < dst_len)
                dst[i] = '\0';

}

int main(void)
{
        int i;
        char srouce[] = "hello every one , good evening!";
        char destination[20]="1234567891234567891";
        copy_n(destination,srouce,10);

        printf("%s\n",destination);

}
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"copy_n_str.c" 33L, 547C written
[root@bjxdurs235 c-study]# gcc copy_n_str.c
[root@bjxdurs235 c-study]# ./a.out
hello ever

过程中遇到的问题有：

1、刚开始没有给destination[20]初始化，结果用gdb调试的时候，传给函数的时候，他内容是：
(gdb) i locals
i = 8286196
srouce = "hello every one , good evening!"
destination = "\000\000\000\000\000\000\000\000\2160"

所以strlen求他的长度，肯定是0了
2、给dst的最后一个元素赋值：'\0'，那个i已经指向最后一个数组元素了，不需要再加1了

好了，自己实现了以后，看看课后的答案吧，答案里没有用strlen判断，而是直接把src的为0的条件拿来判断了，这样不太好，对目的数组的长度肯定是要判断的啊。