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\n",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。