LearnMate

Use the if statement to execute a statement if a logical condition is true. Use the optional else clause to execute a statement if the condition is false. An if statement looks as follows:

if (condition) {
                          // block of code to be executed if the condition is true
                        }

condition can be any expression that evaluates to true or false. See Boolean for an explanation of what evaluates to true and false. If condition evaluates to true, statement_1 is executed; otherwise, statement_2 is executed. statement_1 and statement_2 can be any statement, including further nested if statements.

You may also compound the statements using else if to have multiple conditions tested in sequence, as follows:


                          if (20 > 18) {
                            printf("20 is greater than 18");
                          }

In the case of multiple conditions only the first logical condition which evaluates to true will be executed. To execute multiple statements, group them within a block statement ({ ... }) . In general, it's good practice to always use block statements, especially when nesting if statements:

if (condition) {
                            // block of code to be executed if the condition is true
                          } else {
                            // block of code to be executed if the condition is false
                          }

It is advisable to not use simple assignments in a conditional expression, because the assignment can be confused with equality when glancing over the code. For example, do not use the following code:

int time = 20;
                          if (time < 18) {
                            printf("Good day.");
                          } else {
                            printf("Good evening.");
                          }
                          // Outputs "Good evening."

If you need to use an assignment in a conditional expression, a common practice is to put additional parentheses around the assignment. For example:

int x = 20;
                          int y = 18;
                          if (x > y) {
                            printf("x is greater than y");
                          }