修改C字符串常量？ [英] Modifying C string constants?

问题描述

  

可能重复：结果
  <一href=\"http://stackoverflow.com/questions/164194/why-do-i-get-a-segmentation-fault-when-writing-to-a-string\">Why做写入字符串时，我得到一个分段错误？

我想写反转传递给它给定的字符串的函数。
但是我不能。如果我提供 doReverse 功能（见$ C $下面c）与一个字符数组，我的code效果很好。

我想不通为什么这是行不通的。
我能够访问海峡[0] 在 doReverse ，但我无法改变的数组的任何值使用字符指针。任何想法？

 无效doReverse（字符* STR）{
    海峡[0] ='B';
}无效的主要（无效）{
    char *之海峡=ABC;
    doReverse（STR）;
    看跌期权（STR）;
}
 

更新：

我知道该怎么做传递一个字符数组来写一个反转功能：

 无效reverse1（字符P []）{
    INT I，温度，Y;    对于（I = 0，Y = strlen的（P）; I＆所述; Y; ​​++ i的，--y）{
        TEMP = P [Y-1];
        P [Y-1] = P [I];
        P [i] =温度;
    }
}
 

不过，我想要写另一个版本，获取一个字符指针作为参数。<​​/ P>

解决方案

最简单的解决方法是 STR 的声明更改为

 字符海峡[] =ABC;
 

这使得 STR 字符数组的初始化字符串ABC。目前，你有 STR 作为初始化为指向一个字符串描述一个字符串指针到字符。有一个关键的区别：字符串文字是只读的给编译器在哪里来存储它们最大的灵活性;它是UB修改它们。但字符数组是可变的，所以它的好修改这些。

PS。 的main（）返回 INT 。

Possible Duplicate:
Why do I get a segmentation fault when writing to a string?

I want to write a function that reverses the given string passed into it. But, I can not. If I supply the doReverse function (see code below) with a character array, my code works well.

I can't figure out why this does not work. I am able to access str[0] in doReverse, but I can't change any value of the array by using a char pointer. Any ideas?

void doReverse(char *str) {
    str[0] = 'b';
}

void main(void) {
    char *str = "abc";
    doReverse(str);
    puts(str);
}

Update:

I know how to do write a reverse function by passing a character array to it:

void reverse1(char p[]) {
    int i, temp, y;

    for (i = 0, y = strlen(p); i < y; ++i, --y) {
        temp = p[y-1];
        p[y-1] = p[i];
        p[i] = temp;
    }
}

But, I want to write another version that gets a char pointer as a parameter.

解决方案

The simplest solution is to change the declaration of str to

char str[] = "abc";

This makes str an array of char that is initialized to the string "abc". Currently you have str as a pointer-to-char initialized to point to a string described by a string literal. There is a key difference: string literals are read-only to give the compiler maximum flexibility on where to store them; it is UB to modify them. But arrays of char are mutable, and so it's okay to modify those.

PS. main() returns an int.

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