如何使用指针复制字符串 [英] How to copy a string using a pointer

问题描述

这是我编写的用于复制字符串常量的程序.

Here's a program I wrote to copy a string constant.

程序运行时崩溃.为什么会这样?

When the program is run it crashes. Why is this happening ?

#include <stdio.h>

char *alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char c;
char *l;

main(){
   while((c = *alpha++)!='\0')
       *l++ = *alpha;
   printf("%s\n",l);
}

推荐答案

要在C语言中复制字符串，可以使用strcpy.这是一个示例:

To copy strings in C, you can use strcpy. Here is an example:

#include <stdio.h>
#include <string.h>

const char * my_str = "Content";
char * my_copy;
my_copy = malloc(sizeof(char) * (strlen(my_str) + 1));
strcpy(my_copy,my_str);

如果要避免意外的缓冲区溢出，请使用strncpy而不是strcpy.例如:

If you want to avoid accidental buffer overflows, use strncpy instead of strcpy. For example:

const char * my_str = "Content";
const size_t len_my_str = strlen(my_str) + 1;
char * my_copy = malloc(len_my_str);
strncpy(my_copy, my_str, len_my_str);

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