calloc给longlongint长度的数组分配内存时出错

Question

calloc给longlongint类型的数组分配内存会报警告，数组过长会出错。似乎是参数长度受限。

警告如下：

warning C4244: “参数”: 从“__int64”转换到“size_t”，可能丢失数据

完整代码如下：

#define  _CRT_SECURE_NO_WARNINGS

#include "stdio.h"
#include "stdlib.h"
#include "math.h"

int main(){
    long long int *A, *g, r;
    long long int sub = 0;
    long long int n, N, *f, lg, rg, lf, rf;
    long long int length = 0;
    scanf("%lld %lld", &n, &N);
    r = N / (n + 1);
    A = (long long int *)calloc(n + 2, sizeof(long long int));//报警告
    A[0] = 0;
    A[n + 1] = N;
    f = (long long int *)calloc(N, sizeof(long long int));//报警告
    g = (long long int *)calloc(N, sizeof(long long int));//报警告
    for (int i = 1; i < (n + 1); i++){
        scanf("%lld", &A[i]);
        if (A[i] < N)f[A[i]] = i;
    }
    for (int i = 1; i < N; i++){//完成g[]和f[]
        g[i] = i / r;
        if (f[i] == 0)
            f[i] = f[i - 1];
        else continue;
    }
/*    for (int i = 0; i < N; i++){
        sub += abs(g[i] - f[i]);
    }*/
    for (long long int j = 0; j < n + 1; j++){
        for (long long int i = A[j]; i < A[j + 1]; i += length){
            lg = i;
            lf = i;
            rf = A[j + 1] - 1;
            rg = i + r - 1 - i%r;
            length = (rf>rg ? rg : rf) - i + 1;
            sub += length*(abs(f[i] - g[i]));
        }
    }
    printf("%lld", sub);
    system("pause");
    return 0;
}

是否有方法给longlongint长度的数组动态分配内存，求解答

Answer 1

可以使用unsigned long long类型的数组来代替long long类型的数组。另外，可以使用malloc函数动态分配内存。具体的代码如下：

#define  _CRT_SECURE_NO_WARNINGS

#include "stdio.h"
#include "stdlib.h"
#include "math.h"

int main(){
    unsigned long long int *A, *g, r;
    unsigned long long int sub = 0;
    unsigned long long int n, N, *f, lg, rg, lf, rf;
    unsigned long long int length = 0;
    scanf("%llu %llu", &n, &N);
    r = N / (n + 1);
    A = (unsigned long long int *)malloc((n + 2)*sizeof(unsigned long long int));//使用malloc分配内存
    A[0] = 0;
    A[n + 1] = N;
    f = (unsigned long long int *)malloc(N*sizeof(unsigned long long int));
    g = (unsigned long long int *)malloc(N*sizeof(unsigned long long int));
    for (unsigned long long int i = 1; i < (n + 1); i++){
        scanf("%llu", &A[i]);
        if (A[i] < N)f[A[i]] = i;
    }
    for (unsigned long long int i = 1; i < N; i++){
        g[i] = i / r;
        if (f[i] == 0)
            f[i] = f[i - 1];
        else continue;
    }
    for (unsigned long long int j = 0; j < n + 1; j++){
        for (unsigned long long int i = A[j]; i < A[j + 1]; i += length){
            lg = i;
            lf = i;
            rf = A[j + 1] - 1;
            rg = i + r - 1 - i%r;
            length = (rf>rg ? rg : rf) - i + 1;
            sub += length*(abs(f[i] - g[i]));
        }
    }
    printf("%llu", sub);
    system("pause");
    return 0;
}

注意，使用malloc函数分配内存后，需要使用free函数释放内存，否则会出现内存泄漏的情况。