程序在大输入上崩溃（C）-Programcrashesonlargeinputs(C)

process to fix

修复过程

• use a debugger ( always ) to find the line causing segfault

使用调试器(总是)来查找导致段错误的行

• study the offending variables involved

研究涉及的违规变量

In this case, line 53 was referring to an array2 access which was not properly allocated..

在这种情况下,第53行指的是未正确分配的array2访问。

changes required

• move allocation of array1 after the scanf has properly assigned n

在scanf正确分配n后移动array1的分配

• change the allocation of array2 which was previously assigning malloc return to the contents of the pointer array2 instead of array2 ( which at this stage was also unallocated ) pointer

更改以前分配malloc的array2的分配返回指针array2的内容而不是array2(在此阶段也是未分配的)指针

• adjust allocation to use sizeof(*array1+2) as identified by @alk

调整分配以使用由@alk标识的sizeof(* array1 + 2)

adjusted code

#include 
#include 

int main(int argc, char *argv[])
{
    int i, n, q = 0, k, *array2;

    printf("Geben Sie eine natuerliche Zahl n ein: ");
    scanf("%d", &n);
    int *array = malloc((n-1)*sizeof(*array));
    printf("\n");

    for(i=0; i<=n-2; i++){
        array[i] = i+2;
    }

    while(q<=n-2){
        while(array[q]==0&&q<=n-2){
            q++;
        }
        for(i=q+1; i<=n-2; i++){
            if(array[i]%array[q]==0){
                array[i] = 0;
            }
        }
        q++;
    }

    PART1:
    for(i=0; array[i]!=0; i++){
        if(array[i+1]==0){
            int j;
            for(j=i+1; j<=n-2; j++){
                if(array[j]!=0){
                    array[i+1] = array[j];
                    array[j] = 0;
                    goto PART1;
                }
            }
            k = i;
            goto PART2;
        }
    }

    PART2:
    array2 = malloc((k+1)*sizeof(*array2));

    for(i=0; i<=k; i++){
        array2[i]=array[i];    //Here's where the program crashes
    }

    free(array);

    for(i=0; i