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.
- Initialize and
- If the result of evaluating the conditional expression is true, execute the processing within {}.
- After processing the iterator,
- 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);
}
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;
}