程序编译过程中错误记录

1 越界（做leecode题时显示的错误）

程序如下

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
    int* twoSum(int* nums, int numsSize, int target, int* returnSize){
    int j = 0;      //用来搜索第一个数
    int k = 0;      //用来搜索第二个数
    int *a;
    int flag = 0;
    a = (int *)malloc(sizeof(int) * 2);
    *returnSize = 0;
    for(j = 0; j < numsSize; j++)
    {
        for(k = j + 1; k <= numsSize; k++)
        {
           if(target == nums[j] + nums[k])   //判断两值之和是否为目标值
            {
                *a = j;
                *(a + 1) = k;
                *returnSize = 2;
                flag = 1;
             }
        }
        if(flag == 1)   break;
    }
    return a;
}

编译后结果如下，显示越界

=================================================================
==46==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000000020 at pc 0x0000004019cc bp 0x7ffc46336880 sp 0x7ffc46336870
READ of size 4 at 0x602000000020 thread T0
    #2 0x7f4d0107a82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
0x602000000020 is located 0 bytes to the right of 16-byte region [0x602000000010,0x602000000020)
allocated by thread T0 here:
    #0 0x7f4d02095f88 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x10bf88)
    #3 0x7f4d0107a82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
Shadow bytes around the buggy address:
  0x0c047fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c047fff8000: fa fa 00 00[fa]fa 00 fa fa fa fa fa fa fa fa fa
  0x0c047fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
  Shadow gap:              cc
==46==ABORTING

错误分析：

比如一个数组a[4] = {2,7,11,15};

那么numSize就等于4，而在for循环中，J和K都是下标，

for(j = 0; j < numsSize; j++)//表明J可以取值3

for(k = j + 1; k <= numsSize; k++) //当J为3时，K就为4，而a[4]这个数就越界了。

修改过后通过

2 left operand must be l-value

不能给常量赋值

void main()
{
    int a[4] = {2,7,11,15};
    int b[2] ={0,0};
    b = twoSum(a, 4, 26, b);//只能给变量赋值
    printf("%d,%d
",b[0],b[1]);
}

3 undefined reference to `WinMain@16'

解决方法

4 member access within null pointer of type 'struct TreeNode'

翻译：访问一个空节点的成员

解决方法：在访问之前判断一下该节点是否为空。

参考：leetcode 编译问题：Line x: member access within null pointer of type 'struct TreeNode'

链接：https://www.cnblogs.com/qq952693358/p/9280717.html

5 if语句中的判断条件在改变

if(a[i] > temp)
    temp += a[i];

以上两条语句，本意是想把数组中大于temp的数，就进行累加，但累加后，temp就改变了，判断条件也就改变了。