c - 如何检查变量是否为整数类型

Question

我只是想检查变量中存在的值是否为整数。

My program below reads two values from "myfile.txt" and performs addition if and only if they are integers otherwise it returns "Invalid Output". I have successfully read values from "myfile.txt" but i have no way of checking whether the two values are integer or not.How to perform this test?

#include <stdio.h>
#include <conio.h>

int main()
{
    FILE *fp;
    int i, mkji, num, num1, num2;
    int s = 0;
    int a[2];
    char term, term2;
    clrscr();
    fp = fopen("myfile.txt", "r+");
    if (fp != 0)
    {
        for(i = 0; i < 2; i++)
        {
            fscanf(fp, "%d", &a[i]);
        }
        for(i = 0; i < 2; i++)
        {
            printf("%d\n", a[i]);
        }
        num = a[0];
        num1 = a[1];
        num2 = num + num1;
        printf("%d", num2);
        mkji = fclose(fp);
    }
    else
        printf("FILE CANNOT BE OPEN");
    getch();
    return 0;
}

Answer 1

检查fscanf 的返回值。 fscanf 返回成功扫描的项目数，如果出现 IO 错误，则返回 -1。因此，如果数字格式不正确，fscanf("%d",&a[i]); 应该返回 0。