• Normally, the statements in a program are executed in the order in which they appear in the program. This type of execution is called sequential execution.

• Control structures – define the order of execution of statements.

• Conditional control statements – involves both decision making and branching.

1. if-statement.
2. if-else statement.
3. Nested-if-statement.
4. switch statement.

• if-statement – used to execute a statement or a set of statements conditionally.
• Also called a one-way branching.
• Syntax -

if (condition)
{
statement;
}

• if-else statement – The if statement is used to execute only one action. If there are two statements to be executed alternatively, then if-else statement is used.
• Two-way branching.
• Syntax -

if (condition)
{
statement1;
}
else
{
statement2;
}

• Nested-if statement – If there are more than two alternatives to select, then the nested-if statements are used.
• Enclosing an if statement within another if statement is called the nested-if statement.
• Syntax -

if (condition1)
{
if (condition2)
{
statement1;
}
else
{
statement2;
}
}
else if (condition3)
{
statement3;
}
else
{
statement4;
}

• There are many ways to nest one if-else within the other.

• switch statement – The switch statement provides a multiple way of branching.
• It allows the user to select any one of the several alternatives, depending on the value of an expression.
• Syntax -

switch (expression)
{
case label1 : block1;
break;
case label2 : block2;
break;
.
.
.
case labelmax : blockmax;
break;
case default : dblock;
break;
}

• The expression is of type int or char.
• Depending on the value of an expression, execution branches to a particular case label and then all the statements belonging to that case label are executed.
• The break statement indicates the end of a particular case label and thereby the switch statement is terminated.
• The case default is executed, when the value of an expression is not matched with any of the case labels.
• The semicolons should not be placed at the end of switch (expression).

• goto-statement – an unconditional control statement.
• To transfer the control from one point to another in a C program.
• Syntax -
  

  goto label;

• Forward jump and backward jump.
• Bachward jump will form a loop.
• The use of goto statement in a structured programming language like C should be avoided. Use if and only if it is unavoidable.
• The goto statement may create an infinite loop where the computer enters a permanent loop. The careful and cautious design would resolve such situations.
• A program may contain any number of goto statements.
• No two statements can have the same label.

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