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Saturday, September 26, 2009

Arithmetic operators

Q. What are the Arithmetic Operators in Cobol?
Cobol has five standard arithmetic verbs, ADD, SUBTRACT, MULTIPLY, DIVIDE and COMPUTE. Arithmetic statements can be written in various different forms. Look at the examples below.

The ADD verb adds up the first number TO the second. If you write ADD X TO Y, it means Y + X. If you write ADD X Y TO Z, it means (i) first add X to Z (ii)second add Y to Z. The result of addition is always stored in the second. If an optional GIVING keyword is specified on the ADD statement, the result of the addition is assigned to a third variable.

The SUBTRACT verb subtracts the first number FROM the second. If you write SUBTRACT Y FROM X, it means X – Y. If you write SUBTRACT X Y FROM W, it means (i) first subtract X from W (ii)second subtract Y from W. The difference is stored in the second.

The MULTIPLY verb computes the product of the first times the second. If you write MULTIPLY X BY Y, X is multiplied with Y, and the product is stored in Y. 

When DIVIDE 10 BY 05, the result is 2. If you DIVIDE 3 INTO 6, the result is 2. On dividing 10 BY 3, the remainder is 1.

The COMPUTE verb in Cobol is for writing arithmetic expressions. For example, to calculate the area of a circle, you may write COMPUTE AREA = 3.14159 * (RADIUS ** 2). The COMPUTE Statement has the general form COMPUTE result = arithmetic-expression. On the Left-Hand side(LHS), you write the variable, which shall store the result of computation. On the RHS, you write the arithmetic expression whose value needs to be evaluated.

The table below contains examples of how arithmetic operators in Cobol are used.


Sample Program Listing
A quadratic equation(highest degree=2) has the general form ax2 + bx + c = 0. The formula for calculating the roots of a quadratic equation is image.

A Cobol program has to be designed and coded to compute the quadratic roots, with precision upto four digits after the decimal point.

Program Source

Wednesday, September 2, 2009

Basic Procedure Division Verbs

Q. What is the MOVE verb in Cobol?
When you declare a variable in Cobol, the computer books and reserves memory space for you, to store data. Assume that, I declare a variable in my Cobol program GROSS-PAY.


The variable GROSS-PAY has a picture string 9(04)V99, it is six bytes in size. The computer reserves a six-byte slot in the memory for storing my data, as shown in the picture below. This storage field is identified by the name GROSS-PAY.


The GROSS-PAY variable is empty yet. Storing data in the GROSS-PAY variable can be accomplished using the MOVE statement. The MOVE statement assigns and stores data in a Cobol variable. It is a Data-Transfer verb.


The above MOVE statement transfers the number 1500.00 into the memory location GROSS-PAY.


A MOVE statement may also transfer data from one field(variable) to another field(variable). In the below example, the contents of the variable DEARNESS-ALLOWANCE are transferred, MOVE’d to OUT-DA variable. DEARNESS-ALLOWANCE is said to be the sending field, whereas OUT-DA is the receiving field.


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