Conditionals & Loops

Description of conditional statements and loops

Conditional Statements

Conditional statements are used to perform different actions based on different conditions.

if

The if statement executes some code if one condition is true.

Syntax

if (condition) {
  code to be executed if condition is true;
}

Example 1

if (@rax == 55) {
    printf("rax is equal to %llx\n", @rax);
}

Example 2

if (poi(@rcx + 0x10) == ffff7080deadbeef && @rdx != 55 || $pid == 4) {
    printf("condition is met\n");
}

else

The else statement is executed if the if condition is false.

Syntax

if (condition) {
  code to be executed if condition is true;
}
else {
  if the above condition is false, then else is called;
}

Example

if (@rax == 55) {
    printf("rax is equal to %llx\n", @rax);
}
else {
    printf("rax is not equal to 0x55, it is equal to %llx\n", @rax);
}

elsif

Multiple if...else statements can be nested to create an elsif clause. Note that there is one elsif (in one word) keyword in HyperDbg script engine.

Syntax

if (condition) {
  code to be executed if condition is true;
}
elsif (condition) {
  code to be executed if elsif condition is true;
}
else {
  if none of the above conditions are true, then else is called;
}

Example

if (@rax == 55) {
    printf("rax is equal to 0x55\n");
}
elsif (@rax == 66) {
    printf("rax is equal to 0x66\n");
}
elsif (@rax == 77) {
    printf("rax is equal to 0x77\n");
}
else {
    printf("rax is not equal to 0x55, 0x66, 0x77. It is equal to %llx\n", @rax);
}

Loops

The following statements are used to create loops in HyperDbg's script engine.

for

The for statement creates a loop that consists of three expressions, enclosed in parentheses and separated by semicolons, followed by a block statement to be executed in the loop.

Syntax

for (initial value; condition; incrementation or decrementation) {
  code to be executed in loop;
}

Example 1

for (i = 10; i != 0; i--) { 
    printf("%d\n", i); 
}

Example 2

for (i = 0; i < 10 ; i++) {
    for (j = 0; j < 10; j++) {
        printf("%d, %d\n", i, j); 
   }
 }

while

With the while loop, we can execute a set of statements as long as the condition is true.

Syntax

while (condition) {
  code to be executed if while condition is true;
}

Example

x = 55;
while (x) {
    printf("x = %x\n", x);
    x = x - 1;
}

do, while

The do..while loop is similar to the while loop with one important difference. The body of do...while loop is executed at least once. Only then, the test expression is evaluated.

Syntax

do {
  code to be executed at least one time and continues,
   if while condition is true;
}
while (condition); 

Example

x = 55;
do {
    printf("x = %x\n", x);
    x = x - 1;
} while (x);