Calculator programming in c

 1 /*This is program of calculator*/
 2  /*Author- Programmed guy Rohit*/
 3  #include<stdio.h>
 4  float prod(float,float);
 5  float divide(float,float);
 6  float add(float,float);
 7  float sub(float,float);
 8  int main()
 9  {
10  float n1,n2;
11  char sym,choice;
12  printf("calculator program\n\n" );
13  scanf("%f%c%f",&n1,&sym,&n2);
14  if(sym=='*')
15  printf("\n%f",prod(n1,n2));
16  if(sym=='/')
17  printf("\n%f",divide(n1,n2));
18  if(sym=='+')                           /*demo of nested if*/
19  printf("\n%f",add(n1,n2));
20  if(sym=='-')
21  printf("\n%f",sub(n1,n2));
22  printf("\nWould you like to continue?\n[y/n]\n");   //use choice keyword to
23  scanf("%s",&choice);                                                 //use again this
24  if(choice=='y'||choice=='y')                                      //program
25  main();                                                                        //with yes or no
26  }                                                                                 //option*/
27  float prod(float m1,float m2)
28  {
29  return(m1*m2);
30  }
31  float divide(float m1,float m2)
32  {
33      return(m1/m2);
34  }
35  float add(float m1,float m2)
36  {
37      return(m1+m2);
38  }
39  float sub(float m1,float m2)
40  {
41      return(m1-m2);
42  }
43  

Loop in c programming

 1 #include <stdio.h>
 2  
 3  int
 4  main (void)
 5  {
 6     int time;
 7  
 8     /* the loop */
 9     for (time=60; time>=0; time=time-1)
10     {
11        printf ("%d  ", time);
12     }
13  
14     printf ("\n\nLIFTOFF!\n\n");
15  
16     return(0);
17  }