if Structure

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There are 3 types of "if structure".
1.simple if 
2.if...else structure
3.if...else if ... else structure

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1.Simple if structure

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Checks if a condition is true and executes the code specified. if the condition is false continues the execution of the main program.

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program if1;

var

a:integer;

begin

writeln('Give a :');

readln(a);

if(a>0) then

writeln(a,' > ',0);

end.

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2.if...else structure

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Checks if a condition is valid. if the condition is true then executes the code specified. otherwise executes the else part of code.

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program if1;
var
a:integer;
begin
writeln('Give a :');
readln(a);
if(a>0) then
writeln(a,' > ',0)
else
writeln(a,'<=',0);
end.

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3.if...else if ... else structure

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Checks multiple conditions. Executes the specified code. if none of the conditions is met , then executes the else part of the if structure.

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program if2;

var

a:integer;

begin

writeln('Give a :');

readln(a);

if(a>0) then

writeln(a,' > ',0)

else if (a=0) then

writeln(a,' = ',0)

else

writeln(a,' < ',0);

end.

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