Control structure

Describes control constructs such as conditional branching and repetition.

if - conditional branch

Conditional branching can be realized by dividing the processing with {} after if (conditional expression).

int x = 100;
int y = 200;

if (x == y) {
     // what to do if x == y evaluates to true
} else {
     // What to do if x == y evaluates to false
}

while - repeat

By writing while (conditional expression) { }, you can write a process that repeatedly executes {} until the conditional expression becomes false.

Use break to force exit from the loop.

int x = 0;
while (x < 100) {
     // repeat this process while x is less than 100
     ++x;
}

int y = 0;
// Since the conditional expression is always true, repeat the processing until you explicitly exit with break
while (true) {
     if (y >= 100) {
         // force exit from loop
         break;
     }
     ++y;
}

for - iteration with initialization and iterators

By writing for (initialization; conditional expression; iterator) { }, the following process will occur.

1. Initialize variable,
2. If the result of evaluating the conditional expression is true, execute the processing within {}.
3. After processing the iterator,
4. Check the conditional expression again, and if it is true, return to 2. and repeat the process

Conditional branching is achieved by containing the processing statements in {}.

int i;
for (i = 0; i < 100; ++i) {
     // repeat this process 100 times
     hsSystemOutput("%d\n" %i);
}

Exiting Loops (break, continue)

Using break or continue, you can control execution of loop process.

break

break allows you to exit the loop in the middle of its execution.

int i = 0;
// This loop will continue indefinitely since the condition is always true, unless explicitly exited with break.
while (true) {
    if (i >= 100) {
        // Forcefully exit the loop with break.
        break;
    }
    ++i;
}

continue

continue allows you to skip the remaining loop process and move on to the next iteration.

// This loop displays the value of i 100 times.
for (int i = 0; i < 100; ++i) {
    if (i == 5) {
        // However, when i equals 5, continue skips the rest of the loop, so nothing is displayed.
        continue;
    }
    hsSystemWriteLine("i=%d" % i);
}

switch - Concise description of many branch conditions

switch (value used for condition judgment) {
     case judgment_value_A:
         // Process A
         break;
     case judgment_value_B:
         // process B
         break;
     // ...
}

You can concisely write multiple conditional expressions and the processing to be executed when true for one value.

By putting a default clause at the end of a case, you can write the processing statements when none of the cases are met.

int id = 100;
string message;

switch (id) {
     case -1:
         message = "dummy account";
         break;
     case 0:
         message = "root user";
         break;
     default:
         message = "restricted user";
         break;
}