字符串动态数组成长 [英] Dynamically grown array of strings

问题描述

我试图建立一个字符串的动态数组成长。无论是串数，也不每个字符串的长度是在编译时已知。这里的code，我想出了到目前为止（这只是我的语法扮演）：

I'm trying to build a dynamically grown array of strings. Neither the number of strings nor the length of each string is known at compile time. Here's the code I came up with so far (this is just me playing with the syntax):

char **result = NULL;
char *temp = NULL;
result = (char **)realloc (result,sizeof(char *) * 1);
temp= (char *)realloc(temp,5 * sizeof(char));

strcat(temp,"hello");


temp= (char *)realloc(temp,10 * sizeof(char));

strcat(temp," world");

printf ("%s \n", temp);
result[0]=temp;
free(temp);
printf ("%s \n", result[0]);

result = (char **)realloc (result, sizeof(char *) * 2);
temp= (char *)realloc(temp,10 * sizeof(char));
strcat(temp,"0123456789");

temp= (char *)realloc(temp,15 * sizeof(char));
strcat(temp,"asdfg");

printf ("%s \n", temp);
result[1]=temp;
free(temp);
printf ("%s \n", result[0]);
printf ("%s \n", result[1]);)

现在，当我打印结果[0]，或导致[1]，它只是一个空字符串，为什么不会导致[1] =温度;工作？

Now, when I print result[0] or result[1], its just an empty string, why doesn't result[1]=temp; work?

下面就是我刚才试过了，但它没有工作，我一直在使用最后一行的realloc（）时得到无效的尺寸错误：

Here's what I tried earlier, but it didn't work, I kept getting "invalid size" errors when using realloc() on that last line:

char **result = NULL;
result = (char **)realloc (result,sizeof(char *) * 1);
result[0]= (char *)realloc(result[0],5 * sizeof(char));

strcat(result[0],"hello");
printf ("%s \n", result[0]);

result[0]= (char *)realloc(result[0],10 * sizeof(char));

strcat(result[0]," world");
printf ("%s \n", result[0]);

result = (char **)realloc (result, sizeof(char *) * 2);
result[1]= (char *)realloc(result[1],10 * sizeof(char));
strcat(result[0],"0123456789");

result[0]= (char *)realloc(result[1],15 * sizeof(char));
strcat(result[0],"asdfg");

如果有人可以帮助我得到任一版本的工作，我将非常感激。

If anybody could help me get either version working, I would be very grateful.

更新：好吧，我得到了code工作的两个版本。现在，当我尝试在我的实际程序中使用此相同的格式，我得到的错误，如

UPDATE: Ok, I got both versions of the code working. Now when I try to use this same format in my actual program, I get errors such as

*** glibc detected *** ./uvicfmt3: realloc(): invalid next size: 0x08ed3170 ***

现在在我的计划中，结果被声明为一个全局变量（用我的code的第二版），和realloc函数被调用不同的子程序。那是什么导致这个问题？我怎么能解决这个得到什么？

Now in my program, the "result" is declared as a global variable (using the second version of my code), and the realloc functions are called in different subroutines. Is that what's causing the problem? How could I get around this?

推荐答案

• 在第一个例子中，你使用一个字符串后释放是


• 在您 strcat的 ING未分配的内存中的第二个例子（加上没有受过教育的的realloc（结果[0] 是没有意义的）

• In the first example you are using a string after freeing it
• In the second example you are strcating to unallocated memory (plus the uneducated realloc(result[0] makes no sense)

您可以试试这个：

char **result = NULL;
result = realloc(result, sizeof(char *) * 1);

result[0] = strdup("hello");

/* ... */

result = realloc(result, sizeof(char *) * 2);
result[1] = strdup(" world");

现在的strdup 不是标准，但它并不难偷/捏造事实。这里有一个尝试：

Now strdup isn't standard but it's not hard to steal it / fake it. Here's one attempt:

char *strdup2(const char *str)
{
    size_t len;
    char *rval = NULL;

    len = strlen(str);        /* We should probably check this. */
    rval = malloc(len + 1);   /* And this. */

    memcpy(rval, str, len);
    rval[len] = 0;

    return rval;
}

修改

我以后要修改字符串（可能是错误的）IM pression下。如果不是这种情况，只需将它们存储（无的strdup ）就足够了：

result[0] = "hello";

这篇关于字符串动态数组成长的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！