STRUCTURED PROGRAMMING

• Designing and solving a programming problem using sequence, selection and iteration control instructions are called as structured programming
• It employs a top-down design model, in which the program is divided into modules 

Principles of Structured Programming

• At all times and under all circumstances, the programmer must keep the program within his intellectual grasp 
• The well known methods for achieving this : 
• Top-down design and construction 
• Limited control structures 
• Limited scope of data structures 
• Major elements of structured programming 
• Sequence control structure 
• Selection control structure 
• Iteration control structure 

Rules of Structured Programming

• Code no more than one statement per line. 
• Divide programs into functions. 
• Functions should perform only one task. 
• Variable names should be meaningful. 
• Use of global variables should be avoided. 
• All variables should be explicitly declared and given an initial value. 
• Hierarchical data structures should be used to keep the data and program structured. 
• Each function must have an initial comment 
• Compound conditional statements should be limited to avoid confusion. 
• Indentation should be consistent. 
• When used in functions, the use of { and } should be on their own lines to demark blocks of code. 
• Upper case should be used for defined static constants. 
• For all keywords and variables, use lower case. 

Advantages of Structured Programming

• Easy to write 
• Easy to debug 
• Easy to understand 
• Easy to change