Condensing for 5 for-loops that display an array into 1?

Question

Is there a way to condense five for-loops into one and have them display different variables and letters for each? Currently, I have one loop with five other loops and if/else to keep it condense, but this seems redundant and defeats the very purpose of making the loop.

So I decided to post the whole source code so people can understand what I am trying to get at more. This is a program that creates 100 random grades everytime it runs and I have to sort them, then display them. I am aware I could do 5 for loops, but I want to write code that is more condensed and efficient.

The hard part is writing a loop that can display 5 arrays consistently even though the size of the array changes every run.

#include <iostream>
#include <vector>
using namespace std;

int main(){
    int grades[100];
    int sizeA=0, sizeB=0, sizeC=0, sizeD=0, sizeF=0;
    std::vector<int> gradeA, gradeB, gradeC, gradeD, gradeF;

    srand(time(NULL));

    for(int i = 0; i < 100; i++){
        grades[i] = rand() % 100 + 1;  
    }

    for(int i = 0; i < 100; i++){
        if (grades[i] < 100 || grades[i] > 0){
            if (grades[i]>=90)
                gradeA.push_back(grades[i]);
            else if (grades[i]>=70)
                gradeB.push_back(grades[i]);
            else if (grades[i]>=50)
                gradeC.push_back(grades[i]);
            else if (grades[i]>=20)
                gradeD.push_back(grades[i]);
            else if (grades[i])
                gradeF.push_back(grades[i]);
        } else {
            cout << "uhh.. ";
            return(0);
        }
    }

    sizeA = gradeA.size();
    sizeB = gradeB.size();
    sizeC = gradeC.size();
    sizeD = gradeD.size();
    sizeF = gradeF.size();


    /**toggle ? showgrades(gradeA, size) : (int?)null;**/

}   

Answer 1

How about using a function to do the looping and call it with the required information

void printGrades(const std::vector<int>& grades, char level) {
  cout << num << " " << level << " students: ";
  for(int i = 0; i < grades.size(); i++){
    cout << grades[i] << " ";
  cout << endl;
}

So when you want to print them all:

printGrades(gradeA, 'A');
printGrades(gradeB, 'B');
printGrades(gradeC, 'C');
printGrades(gradeD, 'D');
printGrades(gradeF, 'F');