C Tutorials for Beginners

The if-else Statement As described in earlier post,the if statement will execute a single statement, or a group of statements, when the expression following if evaluates to true.But it does nothing when the expression evaluates to false. In case, we want to execute one group of statements if the expression evaluates to true and another group of statements if the expression evaluates to false,we need to use the If-else statement. The syntax of If-else statement is as follows; if(condition) { statement; } else { statement2; } If the condition 1 is evaluated true,then statement1 will execute else statement2 will be executed. A simple example is; if(a =2500 ) { hra = 1200; da = basic * 0.5 ;pt=150; } else { hra = basic*0.1 ; da = basic * 25.01 / 100 ; } gs = basic + hra + da ; net=gs-pt; printf ( "Net salary = Rs. %f", net ) ; }

The IF statement The C language uses the keyword if to implement the decision control instruction. The general form of IF statement is as follows; if ( condition ) execute this statement ; The condition following the keyword if is always enclosed within a pair of parentheses. If the condition is true then the given statement is executed.If the condition is not true then the statement is not executed; instead the program skips past it. To express conditions in C we use conditional operators. Expression Meaning x == y x is equal to y x != y x is not equal to y x x is less than y x > y x is greater than y x x is less than or equal to y x >= y x is greater than or equal to y Lets consider a sample program; /* The IF statement */ main( ) { int num ; printf ( "Enter a number less than 50 " ) ; scanf ( "%d", &num ) ; if ( num printf ( "You are fail" ) ; } On execution,if you enter a number less than equal to 50 you will get the message on the screen but...

The Decision Control Structure Till now we have used sequence control structure in the programs,in which the various steps are executed sequentially i.e.in the same order in which they appear in the program. In C programing the instructions are executed sequentially,by default. At times,we need a set of instructions to be executed in one situation and an another set of instructions to be executed in another situation. In such cases we have to use decision control instructions.This can be acheived in C using; (a)The if statement (b)The if-else statement (c)The conditional operators