Простой консольный калькулятор - не пойму, где ошибка

#include <stdio.h>
 
int main()
{
    float num1,num2,res,moreCalc;
    char operation;
    printf("============Calculator============\n");
    while(1){
    printf("Please, enter first number: ");
    scanf("%f",&num1);
    printf("Please, enter second number: ");
    scanf("%f",&num2);
    printf("Please, enter operation (+,-,*,/,^): ");
    scanf("%s",&operation);
    switch(operation){
        case '+': res=num1+num2;break;
        case '-': res=num1-num2;break;
        case '*': res=num1*num2;break;
        case '/': res=num1/num2;break;
        default: printf("Wrong move!\n");
    }
    printf("The resault is %.3f\n",res);
    printf("Do you want more calculating? (y/n)\n");
    while(1){
    scanf("%s",&moreCalc);
    if ((moreCalc!='y') || (moreCalc!='n')) {printf("WRONG! You should enter 'y' or 'n'!\n");continue;}
    else break;}
    if (moreCalc=='y') continue;
    else break;}
    return 0;
}

#include <stdio.h>
 
int main()
{
    float num1,num2,res;
    char operation, moreCalc='y';
    printf("============Calculator============\n");
    while(moreCalc!='n'){
        printf("Please, enter first number: ");
        scanf("%f",&num1);
        printf("Please, enter second number: ");
        scanf("%f",&num2);
        printf("Please, enter operation (+,-,*,/,^): ");
        scanf("%s",&operation);
        switch(operation){
            case '+': res=num1+num2;break;
            case '-': res=num1-num2;break;
            case '*': res=num1*num2;break;
            case '/': res=num1/num2;break;
            default: printf("Wrong move!\n");
        }
        printf("The resault is %.3f\n",res);
        printf("Do you want more calculating? (y/n)\n");
        moreCalc='';
        while(moreCalc != 'y' && moreCalc != 'n'){
            scanf("%s",&moreCalc);
            if ((moreCalc!='y') && (moreCalc!='n')) {
                printf("WRONG! You should enter 'y' or 'n'!\n");
                }
        }
    }
    return 0;
}