請問為什麼我的這個程序在vs 2013運行的時候會有問題，但是我卻可以用vs 2010運行？

#include <stdio.h>
#include <math.h>
main()
{
    float data1, data2;
    char op;
    printf("Please enter the expression:\n");
    scanf ("%f %c%f", &data1, &op, &data2);
    switch (op)
    {
    case '+':printf("%f+%f=%f\n", data1, data2, data1 + data2);
        break;
    case '-':printf("%f-%f=%f\n", data1, data2, data1 - data2);
        break;
    case '*':printf("%f*%f=%f\n", data1, data2, data1 * data2);
        break;
    case '/':if (fabs(data2) <= 1e-7)             //与实数0比较
                printf("Division by zero!\n");
             else
                 printf("%f/%f=%f\n", data1, data2, data1 / data2);
        break;
    default: printf("Unknow operator! \n");
    }
}

我在vs 2013運行的時候有把"scanf"改成"scanf_s",可是運行的時候會這樣：