C info and some basic characteristics Cheat Sheet

Loop structure

A loop structure is used to execute a certain set of actions for a predefined number of times or until a particular condition is satisfied. There are 3 control statements available in C to implement loop struct­ures. While, Do while and For statem­ents.

The while statement
Syntax for while loop is shown below:

while(­con­dition)// This condition is tested for TRUE or FALSE. Statements inside curly braces are executed as long as condition is TRUE
{
statement 1;
statement 2;
statement 3;
}

The condition is checked for TRUE first. If it is TRUE then all statements inside curly braces are executed. Then program control comes back to check the condition has changed or to check if it is still TRUE. The statements inside braces are executed repeat­edly, as long as the condition is TRUE. When the condition turns FALSE, program control exits from while loop.

The do while statement
Syntax for do while loop is shown below:

do
{
statement 1;
statement 2;
statement 3;
}
while(­con­dit­ion);

The for statement
Syntax of for statement is shown below:


for(in­iti­ali­zation statem­ent­s;test condit­ion­;it­eration statem­ents)
{
statement 1;
statement 2;
statement 3;
}`

Selective control structure
Selection structures are used to perform ‘decision making‘ and then branch the program flow based on the outcome of decision making. Selection structures are implem­ented in C with If, If Else and Switch statem­ents.

The syntax format of a simple if statement is as shown below.

if (expre­ssion) // This expression is evaluated. If expression is TRUE statements inside the braces will be executed
{
statement 1;
statement 2;
}
statement 1; // Program control is transfered directly to this line, if the expression is FALSE
statement 2;

Syntax format for If Else statement is shown below.

if(exp­ression 1) // Expression 1 is evaluated. If TRUE, statements inside the curly braces are executed.
{ // If FALSE program control is transf­erred to immediate else if statement.

statement 1;
statement 2;
}
else if(exp­ression 2)// If expression 1 is FALSE, expression 2 is evaluated.
{
statement 1;
statement 2;
}
else if(exp­ression 3) // If expression 2 is FALSE, expression 3 is evaluated
{
statement 1;
statement 2;
}
else // If all expres­sions (1, 2 and 3) are FALSE, the statements that follow this else (inside curly braces) is executed.
{
statement 1;
statement 2;
}
other statem­ents;

Switch statement

Switch is a multi branching control statement. Syntax for switch statement is shown below.

switch­(ex­pre­ssion)// Expression is evaluated. The outcome of the expression should be an integer or a character constant
{
case value1: // case is the keyword used to match the intege­r/c­har­acter constant from expres­sion.
//value1, value2 ... are different possible values that can come in expression
statement 1;
statement 2;
break; // break is a keyword used to break the program control from switch block.
case value2:
statement 1;
statement 2;
break;
default: // default is a keyword used to execute a set of statements inside switch, if no case values match the expression value.
statement 1;
statement 2;
break;
}