**C Calculator Program Source Code** : C program with full illustration in comments is given here for making a Calculator in C. You can make this Calculator program to perform any operations you want but we have made this only for following operations:

- Addition
**(a+b)** - Subtraction
**(a-b)** - Multiplication
**(a*b)** - Division
**(a/b)** - Modulus
**(a%b)** - Factorial
**(a!)** - Power
**(a^b)**

Remember you can add any numb er of operations you want to do in this calculator you have to do only these things to add any operation.

- Add a function name in Function Prototype Declaration
- Add a switch case with assigned operator to call the function you have mentioned for calculating the result.
- Print the result or calculated value of the operation in the Function definition of the new added function.

You can make this program in other languages too i.e in C++ , Java , Python, etc. We will upload the other program too soon. Below is the **C program to make a calculator**.

// Calculator Program code using C language #include<stdio.h> #include<math.h> #include<stdlib.h> #include<conio.h> #define KEY "Enter the Operation you want to calculate +,-,*,/,%,^,!:" // Declaring Functions to be used ahead void add(); void subtract(); void multiply(); void divide(); void modulus(); void pow(); int fact(); void calc_op(); // Main Program Logic begins from here int main() { int temp=1; char op; // Function call calc_op(); while(temp) { printf("n"); printf("%s : ", KEY); op=getche(); switch(op) { case '+': add(); break; case '-': subtract(); break; case '*': multiply(); break; case '/': divide(); break; case '%': modulus(); break; case '!': fact(); break; case '^': pow(); break; case 'D': case 'd': calc_op(); break; case 'Q': case 'q': exit(0); break; case 'c': case 'C': clrscr(); calc_op(); break; default : clrscr(); printf("n You have entered unavailable option"); printf(" *n"); printf("n *Please Enter any one of below available "); printf("options n"); calc_op(); } } } //Function Definitions void calc_op() { //clrscr(); to clear screen printf("n C calculator nn"); printf(" * Press 'Q' or 'q' to quit this program or calculator "); printf(" * Press 'D' or 'd' to display options below"); printf("Press 'C' or 'c' to clear the screen display nn"); printf("Enter + for Addition n"); printf("Enter - to Subtract n"); printf("Enter * to Multiply n"); printf("Enter / to Divide n"); printf("Enter % for Modulus operation n"); printf("Enter ^ for X Power Y n"); printf("Enter ! to calculate Factorial nn"); } void add() { int n, sum=0, k=0, number; printf("n How many numbers you want to add:"); scanf("%d",&n); printf("Please enter %d numbers one by one: n",n); while(k<n) { scanf("%d",&number); sum+number; k=k+1; } printf("Sum of %d numbers = %d n",n,sum); } void subtract() { int l, m, n = 0; printf("n Enter the first number : "); scanf("%d", &l); printf("Enter the second number : "); scanf("%d", &m); n=l-m; printf("n%d - %d = %dn", l, m, n); } void multiply() { int a, b, mul=0; printf("n Enter first number : "); scanf("%d", &a); printf(" Enter second number: "); scanf("%d", &b); mul=a*b; printf("n Multiplication of entered numbers = %dn",mul); } void divide() { int a, b, d=0; printf("nPlease enter first number : "); scanf("%d", &a); printf("Please enter second number : "); scanf("%d", &b); d=a/b; printf("nDivision of entered numbers=%dn",d); } void modulus() { int a, b, d=0; printf("n Enter first number : "); scanf("%d", &a); printf(" Enter second number : "); scanf("%d", &b); d=a%b; printf("n Modulus of entered numbers = %dn",d); } void pow() { double a,num, p; printf("nEnter two numbers to find the power n"); printf("number: "); scanf("%lf",&a); printf("power : "); scanf("%lf",&num); p=pow(a,num); printf("n%lf to the power %lf = %lf n",a,num,p); } int fact() { int j,calc_fact=1,num; printf("nEnter a number to find factorial : "); scanf("%d",&num); if (num<0) { printf("n Factorial can be calculated for positive integers only not for negative integers n"); return 1; } for(j=1;j<=num;j++) calc_fact=calc_fact*j; printf("n"); printf("Factorial of the number %d is:%dn",num,calc_fact); return 0; }

**OUTPUT :**

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