测试分数的平均值和没有指针的A，B，C，D，F等级的学生人数

Question

I am trying to make a C++ program counting the number of A, B, C, D, F grades without using Pointers. I thought this would be easy but still have a problem. My code counts the number of C, D, F grade correctly but whenever I input A(90-100) and B(80-89) scores, It displays weird numbers such as 907517809. Why is this working like this? it calculates average score right. This might be a basic question, but I'm curious.. Sorry in advance.

#include <iostream>
using namespace std;

int main(){
int i,testscore,N;
int sum=0;
int Acount,Bcount,Ccount,Dcount,Fcount=0;

std::cout<<"How many test scores? " <<endl;
cin>> N;
    if(N<1){
    std::cout<<"Invalid input. try again"<<endl;
    }
    else if(N>25)
    {
    std::cout<<"1-25 only."<<endl;    
    }
    else if(N>0 && N<25){
    std::cout<<"Total number of test is: "<< N << endl;      
    }
for(i = 0; i < N; i++)
    {
        cout << "Enter the score of students " << i + 1 << ": "; 
        cin >>testscore;

        if(testscore >= 90 && testscore < 100){
        Acount++;
        }

        else if(testscore >= 80 && testscore < 90){
        Bcount++;
        }

        else if(testscore >= 70 && testscore < 80){
        Ccount++;
        }

        else if(testscore >= 60 && testscore < 70){
        Dcount++;
        }
        else if(testscore <60){
        Fcount++;
        }

        sum+=testscore;
    }


std::cout<<"The average test score is: "<<sum/N<<endl;
std::cout<<"The number of A grades: " <<Acount<<endl;
std::cout<<"The number of B grades: " <<Bcount<<endl;
std::cout<<"The number of C grades: " <<Ccount<<endl;
std::cout<<"The number of D grades: " <<Dcount<<endl;
std::cout<<"The number of F grades: " <<Fcount<<endl;

    return 0;
}

Answer 1

Because you've only initialised Fcount to zero. You need to assign all the others too.

int Acount=0,Bcount=0,Ccount=0,Dcount=0,Fcount=0;

You probably already know that without this assignment the variables will have random numbers.

You should be getting a warning about using an uninitialized value. It's good practice to compile in the strictest mode you can. Doing so will help avoid these trivial but time consuming errors.