simple calculator v2.c

// Simple calculator v2

#include<stdio.h>

int main()
{
    char c, str[20], snum1[20],snum2[20];
    int i,snum2length=0,num1,num2;

    printf("\n CALCULATOR (for positive integers only)\n\n");
    printf("\n Enter first number, operator (+,-,*,/) and second number: ");
    scanf("%s",str);

    i=0;
    while(isdigit(str[i]) && str[i]!='\0'){
        snum1[i]=str[i];
        i++;
    }
    snum1[i]='\0';

    num1=atoi(snum1);

    c=str[i];

    i++;
    while(isdigit(str[i]) && str[i]!='\0'){
        snum2[snum2length]=str[i];
        i++;
        snum2length++;
    }

    snum2[snum2length]='\0';

    num2=atoi(snum2);


    printf("\n %d %c %d = ",num1,c,num2);

    switch(c)
    {
        case '+':
            printf("%d \n",num1+num2);
            break;

        case '-':
            printf("%d \n",num1-num2);
            break;

        case '*':
            printf("%d \n",num1*num2);
            break;

        case '/':
            printf("%f \n",(float)num1/num2);
            break;
        default:
            printf("Error! Invalid Operator.");
    }

    printf("\n\n");
    return 0;
}