Fortran Expression and I/O Statement

How to write a simple program in Fortran

As we know computer is a machine which have no mind. It does not understand our language. Computer have own language which converts our input data into its own language. For computer programming in Fortran language each line of the program is written in coding form which is known as Fortran coding form.

For writing a simple Fortran Program follow the following steps:

1) The first line starts with the letter C. This line is known as comment line. Uses of this line gives help to the readers to understand a program. A comment line does not affect the executable program in any way and may be used to provide documentation. This can be understand clearly as above discussed. It can be written in 2nd, 3rd line also.

2) After the comment line first Fortran statement is used which is READ statement. The Fortran statement must be written between columns 7 and 72. All embedded blanks statements are ignored in a Fortran statement. It is written as READ*, input-list.

3) Then other statements according to the program requirement.

4) PRINT statement as PRINT*, output- list as above mentioned.

5) STOP statement instruct the computer to terminate the execution of the program.

6) END statement is the last statement, It informs the compiler to end or finish the program.

These are the steps to make a program in Fortran.

Example:

Here,

C**       THIS IS TESTING OF A PROGRAM

This is the first statement and is called comment statement. It can be written any where in the program. It does not affect the program. It depend upon you whether you want to write it or not.

INTEGER A

This is the second statement. Before giving any variable to the computer it must be declared first. Here the A is declaration of the integer variable.

Now the computer will easily understand the READ statement that variable A is an integer data type.

READ*, A

Here the READ statement tells the computer to read or understand the input list 'A' which is integer variable.

PRINT*, 'THIS IS SURYA'

The PRINT statement will print the value as an output which is as THIS IS SURYA. That means whenever the value or any statement is written in between a single cote, the exact value or the statement displays on the output screen.

Note: When you run this program you must have to type an integer value.

Example:

2, 3,18161 etc. Lastly the program is ended with END statement.

Output of the above program is:

22 THIS IS SURYA

Here the input is given as 22 an integer number and the output comes as THIS IS SURYA

Output:

Program:

In the above program the first four lines are comment lines. The first PRINT statement is used to display the exact line as given in the print statement as: ENTER THE VALUE OF CENTIGRADE READ statement is used as input statement. i.e. the compiler of Fortran will read the given variable as: CENT, which is centigrade. The next PRINT statement print the value of Fahrenheit and the value on the screen displays as: THE VALUE OF FAHRENHEIT IS= <value of variable FAHR>.

Output:

In the above program when you will run it, the first line tell you to enter the value of centigrade. After being given the value of centigrade the output will display as the value of Fahrenheit as shown in the above output.