SIMPLE CALCULATOR

/* C programme to creat simple calculator */
#include <stdio.h>
float add(float a,float b);
float substract(float a,float b);
float multiply(float a,float b);
float divide(float a,float b);
int main(void)
{
     float num1,num2;
     float w,result=6;
     char ch,c;
     printf("Enters two numbers to add,substract,multiply or divide\n");
     scanf("%f %f",&num1,&num2);
     printf("enter a to add, s to substract ,m to multiply,d to divide\n");
     scanf("%c %c",&c,&ch);
     if(ch=='a'||ch=='A')
     {
         result=add(num1,num2);
         printf("%f\n",result);
     }
     else if(ch=='s'||ch=='S')
     {
         result=substract(num1,num2);
         printf("%f\n",result);
     }
     else if(ch=='m'||ch=='M')
     {
         result=multiply(num1,num2);
         printf("%f\n",result);
     }
     else if(ch=='d'||ch=='D')
     {
         result=divide(num1,num2);
         printf("%f\n",divide(num1,num2));
     }
     else
     {
         printf("please input the correct character\n");
     }
     return 0;
}
float add(float a,float b)
{
     float add;
     add=a+b;
     return add;
}
float substract(float a,float b)
{
     float substract;
     substract=a-b;
     return substract;
}
float multiply(float a,float b)
{
     float multiply;
     multiply=a*b;
     return multiply;
}
float divide(float a,float b)
{
     float divide;
     divide=(float)a/(float)b;
     return divide;
}