"conversion to 'float' from 'int' may alter its value"

Question

I researched the error and haven't been able to find it. Also I am new to this. I want to learn the basics of C and here is my first program. I want to modify sum in the function calc so it is a float in case someone divides for example 2/5.

#include <stdio.h>

int getNumber1() {
    int myNumber1;
    printf("\n gib eine Zahl ein: ");
    scanf("%d", &myNumber1);
    return myNumber1;
}

int getNumber2() {
    int myNumber2;
    printf("\n gib eine weitere Zahl ein: ");
    scanf("%d", &myNumber2);
    return myNumber2;
}

char getOp() {
    char myOp;
    printf("\n gib einen Operanten ein: ");
    scanf(" %c", &myOp);
    return myOp;
}

void calc(int number1, int number2, char op) {
    if (op == '+') {
        int sum = number1 + number2;
        printf("\n\n%d %c %d = %d", number1, op, number2, sum);
    }
    if (op == '-') {
        int sum = number1 - number2;
        printf("\n\n%d %c %d = %d", number1, op, number2, sum);
    }
    if (op == '*') {
        int sum = number1 * number2;
        printf("\n\n%d %c %d = %d", number1, op, number2, sum);
    }
    if (op == '/') {
        float sum = number1 / number2;
        printf("\n\n%d %c %d = %.2f", number1, op, number2, sum);
    }
}

int main() {
    int cont = 1;
    while (cont == 1) {
        int number1 = getNumber1();
        int number2 = getNumber2();
        char op = getOp();
        calc(number1, number2, op);
        printf("\nMoechten Sie weitere Berechnungen durchfuehren? (1 fuer Ja, 0 fuer Nein): ");
        scanf("%d", &cont);
    }
    printf("\nDanke und auf Wiedersehen.");
    return 0;
}

But I get the error that conversion to float from int may alter its value. Why is that and how can I solve the error?

Answer 1

The compiler issues the message because an integer value is assigned to a variable of the floating type float.

In this statement

float sum = number1 / number2;

the expression number1 / number2 is evaluated using the integer arithmetic. So assigning to a variable of the type float does not make a great sense.

Instead write for exameple

float sum = ( float )number1 / number2;