c - C 的评分点

Question

这是我的代码，一切正常，但是当我输入任何字母而不是数字时，它显示 A-。 我只是想知道为什么会发生这种情况。为什么只显示 A-。任何人都可以解释为什么会发生这种情况吗？

#include<stdio.h>
int main(){
int num;
printf("Enter Your number ");
scanf("%d" ,& num);
    if(num>79)
    {
   printf("Congratulation you got A+");
}

else if(num>69)
{
printf("Congratulation you got A ");
}
else if(num>59)
{
printf("Congratulation you got A-");
}
else if(num>49)
    {
    printf("Congratulation you got B");
}
else if(num>39)
{
    printf("Congratulation you got C");
}

else if(num>32)
    {
    printf("Congratulation you got D");
}
else
{
    printf("You are a student like me(Shuvo) \nBetter Luck next time");

}
return 0 ;
}

Answer 1

在使用变量 num 之前将其初始化为。我的意思是替换“int num;”行通过“int num = 0;”。这是我的解决方案

 #include <stdio.h>

int main(){
    int num = 0;
    printf("Enter Your number ");
    scanf("%d", &num);
    if (num > 79)
    {
        printf("Congratulation you got A+");
    }

    else if (num > 69)
    {
        printf("Congratulation you got A ");
    }
    else if (num > 59)
    {
        printf("Congratulation you got A-");
    }
    else if (num > 49)
    {
        printf("Congratulation you got B");
    }
    else if (num > 39)
    {
        printf("Congratulation you got C");
    }

    else if (num > 32)
    {
        printf("Congratulation you got D");
    }
    else
    {
        printf("You are a student like me(Shuvo) \nBetter Luck next time");

    }
    return 0;
}