Tutorial

What are else if clause?

Things to remember while using else if clause

• You can use any number of else if clause in this ladder.
• Usage of else in the last is completely optional. It means its up to you that you either want to include it or not in your program.
• This does not destroy the readability of the program.
• By using else-if clause, our program does not creep to the right due to indentation.

• Student should be male. His marks should be more than 80% in 12th and his age should be at least 18 years.
• Student should be female. Her marks should be more than 75% in 12th and her age should be at least 17 years.
• Student should be played at any national level game. Age and qualification doesn’t matter in this case.

#include <stdio.h>

void main ()
{
 int per, age;
 char gen, game;

 printf("Press M for male 
 F for female 
 Y for Yes in game 
 N for No in game 
");
 printf("Enter gender, age and percentage in class 12th 
");
 scanf("%c %d %d",&gen, &age, &per);
 printf("Did you play in any game at national level 
");
 scanf("%c",&game);

 if ((age>=18 && per>=80 && gen==M) || (age>=17 && per>=75 && gen==F))
  prinf("You can take admission in our college.");
 else if (game==Y)
  printf("You can take admission based on sports Kota");
 else
  printf("You cannot take admission in our college.");
}

Output

Explanation

• In the beginning we gave some instructions to user that how he/she should enter the data in our program.
• After that we printed the message and take some details from the student.
• Now basically we have 2 conditions. At first we have to check the student if he/she eligible for general kota and in the last we have to check if he/she is eligible for sports kota.
• To make things a bit clear I checked the results for general kota by using if keyword. I combined the conditions by using logical operators to make the program a bit compact.
• After that by using else if clause I have checked if the student is eligible for sports kota.
• If nothing works then I have also given the default else block to print the message “You cannot take admission in our college.”

Preprocessor Directives in C

Types of Preprocessor Directives in C

Macros

//C program to calculate area of circle

#include <stdio.h>

#define PI 3.14  //macro

int main()
{
 float r, a;
 printf("Enter radius of the circle
");
 scanf("%f",&r);
 a=PI*r*r;
 printf("Area of the circle is %f",a);
 
 return 0;
}

• A macros always start with #define. In our program #define PI 3.14 is the macros definition. Wherever PI is encountered in the program it is replaced with 3.14. 
• In the compilation of the program all the macros definition replaced with the values which are used with #define. It is done in the process when source code is converted into expanded source code.
• Do not add semicolon at the end.
• Generally macros are written in single line. If you want to write it in multiple lines then you have to use macro continuation operator i.e. . An example for this is given below.

Macros with arguments

//C program to calculate perimeter of circle

#include<stdio.h>

#define PERI(x) (2*3.14*x)  //macro with argument

int main()
{
 float r,per;
 printf("Enter radius of the circle
");
 scanf("%f",&r);
 per=PERI(r);
 printf("Perimeter of the circle is %f",per);

  return 0;
}

• In the above program I have used macros with argument with the statement #define PERI(x) (2*3.14*x)
• Be careful while defining macros with arguments. In above example there must be no space between PERI and (x). The body of the macro should be placed in parentheses.
• Whenever the macro calling is done in our program, its calling statement in replaced by its body.
• They are fast as compared to functions because control do not goes to macro definition, the whole body comes at the place where calling is done.

File Inclusion