Stage 2: Control Structures in C++

Control Flow in C++

Control structures allow a program to make decisions and repeat operations. For your exam, it is crucial to understand the differences between various loops and how to construct logical conditions correctly.

1. Conditional Statements

if and else

The fundamental way to branch code. Remember the priorities of logical operators (&&, ||, !).

cpp

int x = 10;
if (x > 0 && x <= 10) {
    std::cout << "X is in range (0, 10]" << std::endl;
} else {
    std::cout << "X is out of range" << std::endl;
}

switch

Use this when checking a single variable (integral type or char) against multiple specific values. Don't forget the break keyword!

cpp

char grade = 'A';
switch (grade) {
    case 'A': std::cout << "Excellent!"; break;
    case 'B': std::cout << "Good"; break;
    default: std::cout << "Other grade";
}

2. Loops (Iterations)

for loop

Ideal when you know in advance how many times an operation should repeat (e.g., traversing an array).

cpp

for (int i = 0; i < 5; i++) {
    std::cout << "Iteration: " << i << std::endl;
}

while and do-while loops

while: Checks the condition before executing the code block (may not run at all).
do-while: Checks the condition after executing the block (always runs at least once).

cpp

int i = 0;
while (i < 3) {
    i++;
}

do {
    // Will run once even if i >= 3
} while (i < 3);

Common Exam Pitfalls

Semicolon after if or for: if (x > 0); will cause the statement below to always execute because the if ends at the semicolon.
Assignment vs. Comparison: if (x = 5) will always be true (as the assignment returns 5); use if (x == 5).
Off-by-one error: Make sure your loop should end at i < n or i <= n.

Control Flow in C++

1. Conditional Statements

if and else

The fundamental way to branch code. Remember the priorities of logical operators (&&, ||, !).

cpp

int x = 10;
if (x > 0 && x <= 10) {
    std::cout << "X is in range (0, 10]" << std::endl;
} else {
    std::cout << "X is out of range" << std::endl;
}

switch

Use this when checking a single variable (integral type or char) against multiple specific values. Don't forget the break keyword!

cpp

char grade = 'A';
switch (grade) {
    case 'A': std::cout << "Excellent!"; break;
    case 'B': std::cout << "Good"; break;
    default: std::cout << "Other grade";
}

2. Loops (Iterations)

for loop

Ideal when you know in advance how many times an operation should repeat (e.g., traversing an array).

cpp

for (int i = 0; i < 5; i++) {
    std::cout << "Iteration: " << i << std::endl;
}

while and do-while loops

while: Checks the condition before executing the code block (may not run at all).
do-while: Checks the condition after executing the block (always runs at least once).

cpp

int i = 0;
while (i < 3) {
    i++;
}

do {
    // Will run once even if i >= 3
} while (i < 3);

Common Exam Pitfalls

Semicolon after if or for: if (x > 0); will cause the statement below to always execute because the if ends at the semicolon.
Assignment vs. Comparison: if (x = 5) will always be true (as the assignment returns 5); use if (x == 5).
Off-by-one error: Make sure your loop should end at i < n or i <= n.

Stage 2: Control Structures in C++

Control Flow in C++

1. Conditional Statements

if and else

switch

2. Loops (Iterations)

for loop

while and do-while loops

Common Exam Pitfalls

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Stage 11: Pointer Arithmetic in C++

Stage 10: Pointers, Address-of, and Dereference Operators

Stage 6: C-Style String Handling (char[])

Stage 2: Control Structures in C++

Control Flow in C++

1. Conditional Statements

if and else

switch

2. Loops (Iterations)

for loop

while and do-while loops

Common Exam Pitfalls

You might also like

Stage 11: Pointer Arithmetic in C++

Stage 10: Pointers, Address-of, and Dereference Operators

Stage 6: C-Style String Handling (char[])