Logic statements

TIP

The logic statement of MCFPP is totally the same as in C/Java. You can skip this chapter if you already know it.

if statement

if statement is a condition statement, it can used to determine a condition is true or false. If true, then the code in the if statement block will be execute. The grammar of if is:

if (condition){
    #code
}

condition is a boolean expression, it’s value is true or false. If the value of condition is true, then #code will be execute.

if statement can be used together with else statement, else statement used to execute the code when the condition in ifis false. The grammar of if-else is shown:

if (condition){
    #code1
}else{
    #code2
}

condition is a boolean expression, it’s value is true or false. If the value of condition is true, then `#code1‘ will be execute; Else, ’#code2‘ will be execute.

We can use else if to add another condition when if is false. The grammar of if-else if-else is shown below:

if (condition1){
    #code1
}else if (condition2){
    #code2
}else{
    #code3
}

while statement and do-while statement

while is a loop statement, it can execute a code block repeatedly, until the condition is false. The grammar of while statement is:

while (condition){
    #code
}

condition is an boolean expression, when condition is true, it’ll execute the code block in #code. Then, determine the value of condition again. If value of condition is true, then #code will be execute; loop again and again, until the value of condition is false.

do-while statement is similar with while statement, but no matter the condition is true or false, it’ll execute the statement in the loop once, and then determine the condition to see continue execution or not. The grammar of do-while is shown below:

do{
    #code
}while (condition);

for statement

for statement is a more complex version of loop, it’s grammar is:

for (forinit; condition; forupdate){
    #code
}

forinit is an initialization expression, used to initialize loop variable. condition is a boolean expression, used to determine if the loop keeps going on. forupdate is a update expression, used to update the variable of the loop. #code represents the loop body, which is the code in the loop. The execute process of for is shown below:

1. Execute forinit, initialize the loop variable.
2. Determine the value of condition, if the value of condition is true, execute #code, then execute forupdate, to update the loop variable, and determine the value of condition again.
3. If the value of condition is false, exit the loop.

In for loop, the declaration of variable forinit only valid in the for loop.

break and continue statement

break statement used to jump out the whole loop, continue statement used to skip the current loop. For example:

for (int i = 0; i < 10; i++){
    if (i == 5){
        break;
    }
    if (i == 3){
        continue;
    }
    #code
}

In this example, when the value of i is 5, breakwill jump out of the loop; when the value of i is 3, continue will jump this loop, go to the next loop directly. So, the change of I in each loop are:0，1，2，4，5, and finally jump out.

break and continue statement only can be used in the loop