C语言扩展动态内存报错：realloc(): invalid next size: 0x0000000002365010 ***

　　晚上被这个内存扩展崩溃的问题折腾的有点崩溃，当答案揭晓的那一刻，恍然大悟，原来如此简单。

　　练习题目：输入一个字符串，根据字母进行排序，说白了就是一个简单的冒泡

#include <stdio.h>

#include <stdlib.h>

#include <stdbool.h>

#include <string.h>

#define BUF_LEN 100

#define COUNT 5

int main(void)

{

        char buf[BUF_LEN];

        size_t str_count = ;

        size_t capacity = COUNT;

        char **pS = calloc(capacity, sizeof(char*));

        char **psTemp = NULL;

        char *pTemp = NULL;

        size_t str_len = ;

        bool sorted = false;

        printf("Enter strings to be sorted, one per line. Press Enter to end:\n");

        char *ptr = NULL;

        while(true)

        {

                ptr = fgets(buf, BUF_LEN, stdin);

                if(!ptr)

                {

                        printf("Error reading string.\n");

                        free(pS);

                        pS = NULL;

                        return ;

                }

                if(*ptr == '\n')

                        break;

                if(str_count == capacity)

                {

                        capacity += capacity/;

                        if(!(psTemp = realloc(pS, capacity)))

                                return ;

                        pS = psTemp;

                }

                str_len = strlen(buf) + ;

                if(!(pS[str_count] = malloc(str_len)))

                        return ;

                strcpy(pS[str_count++], buf);

        }

        while(!sorted)

        {

                sorted = true;

                size_t i = ;

                for(; i < str_count - ; i++)

                {

                        if(strcmp(pS[i], pS[i+]) > )

                        {

                                sorted = false;

                                pTemp = pS[i];

                                pS[i] = pS[i+];

                                pS[i + ] = pTemp;

                        }

                }

        }

        printf("Your input sorted in ascending sequence is:\n\n");

        size_t i = ;

        for(; i < str_count; i++)

        {

                printf("%s", pS[i]);

                free(pS[i]);

                pS[i] = NULL;

        }

        free(pS);

        pS = NULL;

        return ;

}

　　上面标黄处，首先是通过calloc进行内存分配，初始是capacity的长度是5，接着判断当输入的字符串个数等于5了，那么就动态的扩展内存，继续按25%的速度增长。就是在扩展这里，一直报错：

*** Error in `./program714.out': realloc(): invalid next size: 0x0000000002365010 ***

======= Backtrace: =========

/lib64/libc.so.(+0x7f5d4)[0x7f476bff35d4]

/lib64/libc.so.(+0x83bd8)[0x7f476bff7bd8]

/lib64/libc.so.(realloc+0x1d2)[0x7f476bff9832]

./program714.out[0x4008ea]

/lib64/libc.so.(__libc_start_main+0xf5)[0x7f476bf963d5]

./program714.out[0x400729]

======= Memory map: ========

- r-xp  fd:                             /home/wlf/practice/program714.out

- r--p  fd:                             /home/wlf/practice/program714.out

- rw-p  fd:                             /home/wlf/practice/program714.out

- rw-p  :                                   [heap]

7f4764000000-7f4764021000 rw-p  :

7f4764021000-7f4768000000 ---p  :

7f476bd5e000-7f476bd73000 r-xp  fd:                      /usr/lib64/libgcc_s-4.8.-.so.

7f476bd73000-7f476bf72000 ---p  fd:                      /usr/lib64/libgcc_s-4.8.-.so.

7f476bf72000-7f476bf73000 r--p  fd:                      /usr/lib64/libgcc_s-4.8.-.so.

7f476bf73000-7f476bf74000 rw-p  fd:                      /usr/lib64/libgcc_s-4.8.-.so.

7f476bf74000-7f476c136000 r-xp  fd:                      /usr/lib64/libc-2.17.so

7f476c136000-7f476c336000 ---p 001c2000 fd:                      /usr/lib64/libc-2.17.so

7f476c336000-7f476c33a000 r--p 001c2000 fd:                      /usr/lib64/libc-2.17.so

7f476c33a000-7f476c33c000 rw-p 001c6000 fd:                      /usr/lib64/libc-2.17.so

7f476c33c000-7f476c341000 rw-p  :

7f476c341000-7f476c363000 r-xp  fd:                      /usr/lib64/ld-2.17.so

7f476c557000-7f476c55a000 rw-p  :

7f476c55e000-7f476c562000 rw-p  :

7f476c562000-7f476c563000 r--p  fd:                      /usr/lib64/ld-2.17.so

7f476c563000-7f476c564000 rw-p  fd:                      /usr/lib64/ld-2.17.so

7f476c564000-7f476c565000 rw-p  :

7ffde3137000-7ffde3158000 rw-p  :                           [stack]

7ffde31c5000-7ffde31c7000 r-xp  :                           [vdso]

ffffffffff600000-ffffffffff601000 r-xp  :                   [vsyscall]

Aborted

　　代码看来看去发现没毛病，唯一能怀疑的地方就是内存扩展的那一行，经过几番折腾，发现只要一到需要增长调用realloc就报错，最后回去看calloc，只能一拍大腿骂娘了，字节计算的类型不对啊，一个是按char*（相当于二维数组pS[][]中的子数组pS[]）来计算字节，一个是按字符（char）来计算字节，得到的内存大小必然不同啊。把realloc的第二个参数加上这个就解决了：　　

if(!(psTemp = realloc(pS, capacity*sizeof(char*))))

　　编码需谨慎，差之毫厘，谬之千里，一点小小的bug都能让程序崩溃。

巴特西

C语言扩展动态内存报错：realloc(): invalid next size: 0x0000000002365010 ***

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