Switch statement not showing any kind of output other than the default statement

Question

I am writing a switch statement example and everything is fine, no error is given and it runs fine but it's not doing what I want it to do. It shows no output at all, any suggestions please?

I don't know what to try because there is no error, it just doesn't work

 #include <iostream>
 using namespace std;
 main ()
 {
    int student,average,grade,sum;
    char A,a,B,b,C,c,D,d,F,f;
    student = 1;
    average,sum = 0;
    cout << "Please enter the grades of student:";
    cin >> grade;
    switch (grade)
     {
    case 'A' :
    case 'a' :
        cout << "excellent";
        break;
    case 'B' :
    case 'b' :
        cout << "very good";
        break;
    case 'C' :
    case 'c' :
        cout << "good";
        break;
    case 'D' :
    case 'd' :
        cout << "Poor";
        break;
    case 'F' :
    case 'f' :
        cout << "Fail";
        break;
        default:
        cout << "Please enter the grade from A to D & F";
     }
  }

I want it to tell me the remarks of the student's grade but it doesn't show anything at all and it will always show the default message no matter what you enter

Answer 1

You need to make grade a char, not an int.

cin >> grade; is trying to read an integer from the input stream, because grade is an int. If you make grade a char, cin >> grade will read just a single character. (In both cases, it first skips whitespace, so you cannot read a single whitespace character. But that doesn't matter here.)

It's probably worth adding that when you try to read a number and there is no number to read (because the user typed a letter grade) then the input stream is put into an error state. Until the error is reset with std::cin.clear() any input attempt will fail without reading anything. See std::istream::clear, especially the example code provided.

Answer 2

Okay so i asked this question yesterday and thank you guys for your help i used getchar to the the answer but honestly i didn't knew what was the purpose of getchar because i didn't learned it yet so i kept trying and i solved it at last i am posting this only because you guys shared your knowledge and helped me so i want to share what i learned to increase your knowledge the code is here

#include <iostream>
using namespace std;
main ()
{
    char grade;
    cout << "Please enter the grades of student:";
    cin >> grade;
    switch (grade)
    {
        case 'A' :
        case 'a' :
            cout << "excellent";
            break;
        case 'B' :
        case 'b' :
            cout << "very good";
            break;
        case 'C' :
        case 'c' :
            cout << "good";
            break;
        case 'D' :
        case 'd' :
            cout << "Poor";
            break;
        case 'F' :
        case 'f' :
            cout << "Fail";
            break;
            default:
            cout << "Please enter the grade from A to D & F";
    }
}

Answer 3

This should work. I used getchar() instead of cin cause getchar will only get one character (char=single character, string multiple characters). If you use cin and a user type in more then one character, cin will only use the first character.

Another point is your declaration of char a-f,A-B. This is useless. A, B, C, D,E,F are just names, you have to compare to a value. In your own switch you not using all of these chars, you compare them with a character not with a variable. case 'A': check if grade=='A'NOT if grade==a.

Another point is this: average,sum=0 . I dont really now what you want to do but if you trying to set them booth to 0 thats the wrong way. Then you should do in in the declaration like int student, average=0,sum=0; . You declared 3 integers, give them a value but never used them, maybe later? I changed main() to int main() (returntype=integer) More information about the main: What is the proper declaration of main?

I added return 0; to the main, cause a function should have return!

I also added linebreaks to your output to make it better to read from the console.

i commented thinks out where i think they are useless or wrong. If you have any questions or if i did a mistake pls let me know.

#include <iostream>
using namespace std;
int main ()
 {
    int student, average=0,sum=0; //dont know for what these integers are. All getting set but never been used.
     //char A,a='a',B,b,C,c,D,d,F,f; //Completly Useless and not used
    char grade;
    student = 1;
 // average,sum = 0;      What is the expected result of this?!

  cout << "Please enter the grades of student:\n";
  //cin >> grade; replaced with getchar();
    grade=getchar(); //get single char from console

    switch (grade)
     {
    case 'A' :
    case 'a' :
        cout << "excellent\n";
        break;
    case 'B' :
    case 'b' :
        cout << "very good\n";
        break;
    case 'C' :
    case 'c' :
        cout << "good\n";
        break;
    case 'D' :
    case 'd' :
        cout << "Poor\n";
        break;
    case 'F' :
    case 'f' :
        cout << "Fail\n";;
        break;
        default:
        cout << "Please enter the grade from A to D & F\n";
        break;
     }
    return 0;
  }