“运行时检查失败＃2：围绕变量'dayc'的堆栈已损坏”

Question

我正在用C编写一个程序，要求用户输入一个等级7天的温度，程序会将这些温度转换为相反的温度。请注意，当用户输入华氏温度时，我也应该写这个案例，但我还没有。

#include <stdio.h>
#define N 7

float CELC(float x)
{
    float c;
    c = (x*(9.0/5.0))+32;
}

void TempConverter(void)
{
    char cmd;
    float x, b, c, dayc[N], dayf[N];
    int i;

    printf("\nHello, this program converts the temperatures of the last week from one scale to another.\n");
    printf("\nWhat is the scale of the temperature degrees you want to enter?\n");
    printf("\nPlease enter f for Fahrenheit and c for Celsius:\n\n");
    scanf_s("%c", &cmd);

    if (cmd == 'c')
    {
        for (i = 1; i < 8; i++)
        {
            printf("\nPlease enter the temperature of day %d: ", i);
            scanf_s("%f", &dayc[i]);
            if (dayc[i] > 60.0 || dayc[i] < -50.0)
            {
            printf("\nThis is an invalid temperature, please enter a different value\n");
            --i;
            continue;
        }
        dayc[i] = CELC(dayc[i]);
    }

    printf("\nYour equivalent Fahrenheit temperatures are as follows:\n");

    for (i = 0; i < N; i++)
    {
        printf("\nThe temperature of day %d:%f\n", i+1, dayc[i]);
    }
}

}

出于某种原因，我一直收到运行时错误，然后我已经转换为华氏温度的温度变得怪异。我很确定这个问题与我对dayc的使用有关，但我不知道该怎么办。

Here is a picture of my output.