C++ Basics Skill
Production-Grade Learning Skill | Foundation Building
Master the essential building blocks of C++ programming.
Topics Covered
1. Variables & Data Types
cpp
#include <iostream>
#include <cstdint> // Fixed-width integers
int main() {
// ─────────────────────────────────────────────────
// Integer Types (with guaranteed sizes)
// ─────────────────────────────────────────────────
int8_t tiny = 127; // 1 byte, -128 to 127
int16_t small = 32767; // 2 bytes
int32_t normal = 2147483647; // 4 bytes
int64_t large = 9223372036854775807; // 8 bytes
// Unsigned variants
uint8_t ubyte = 255; // 0 to 255
uint32_t ucount = 4294967295; // 0 to 4B
// ─────────────────────────────────────────────────
// Floating Point
// ─────────────────────────────────────────────────
float f = 3.14f; // ~7 decimal digits
double d = 3.14159265358979; // ~15 decimal digits
// ─────────────────────────────────────────────────
// Character & Boolean
// ─────────────────────────────────────────────────
char c = 'A'; // ASCII character
bool b = true; // true or false
// ─────────────────────────────────────────────────
// Modern C++ Initialization (prefer brace init)
// ─────────────────────────────────────────────────
int x{42}; // Brace initialization
auto y = 3.14; // Type deduction (double)
auto z{10}; // int
return 0;
}
2. Operators
| Category | Operators | Example |
|---|---|---|
| Arithmetic | + - * / % | 10 / 3 = 3 |
| Comparison | == != < > <= >= | 5 == 5 → true |
| Logical | && || ! | true && false → false |
| Bitwise | & | ^ ~ << >> | 0xFF & 0x0F → 0x0F |
| Assignment | = += -= *= /= | x += 5 |
| Increment | ++ -- | ++i (prefer prefix) |
3. Control Flow
cpp
// ─────────────────────────────────────────────────────
// Conditionals
// ─────────────────────────────────────────────────────
if (score >= 90) {
grade = 'A';
} else if (score >= 80) {
grade = 'B';
} else {
grade = 'F';
}
// Switch with C++17 init
switch (int x = getValue(); x) {
case 1: std::cout << "One\n"; break;
case 2: std::cout << "Two\n"; break;
default: std::cout << "Other\n"; break;
}
// ─────────────────────────────────────────────────────
// Loops
// ─────────────────────────────────────────────────────
// For loop (prefer prefix ++)
for (int i = 0; i < n; ++i) { }
// Range-based for (C++11)
for (const auto& item : container) { }
// While
while (condition) { }
// Do-while (runs at least once)
do { } while (condition);
4. Functions
cpp
// ─────────────────────────────────────────────────────
// Function declaration
// ─────────────────────────────────────────────────────
int add(int a, int b); // Declaration
void greet(std::string_view name); // string_view for efficiency
// ─────────────────────────────────────────────────────
// Definition with default parameter
// ─────────────────────────────────────────────────────
int add(int a, int b) {
return a + b;
}
void greet(std::string_view name = "World") {
std::cout << "Hello, " << name << "!\n";
}
// ─────────────────────────────────────────────────────
// Pass by reference (for modification or large objects)
// ─────────────────────────────────────────────────────
void increment(int& value) {
++value;
}
void process(const std::vector<int>& data) { // const ref for read-only
for (int x : data) { /* ... */ }
}
// ─────────────────────────────────────────────────────
// Function overloading
// ─────────────────────────────────────────────────────
int max(int a, int b) { return (a > b) ? a : b; }
double max(double a, double b) { return (a > b) ? a : b; }
Troubleshooting
Common Errors
| Error | Cause | Fix |
|---|---|---|
undefined reference | Missing function definition | Add function body |
expected ';' | Missing semicolon | Check previous line |
undeclared identifier | Variable not declared | Declare before use |
narrowing conversion | Data loss in brace init | Use explicit cast |
Decision Tree
code
Compilation error?
├── "undefined reference"
│ └── Function declared but not defined → Add definition
├── "expected ';'"
│ └── Missing semicolon → Check line above error
├── "undeclared identifier"
│ └── Variable not in scope → Declare or check spelling
└── "no matching function"
└── Wrong argument types → Match function signature
Unit Test Template
cpp
#include <cassert>
void test_basics() {
// Test integer operations
assert(add(2, 3) == 5);
assert(add(-1, 1) == 0);
// Test floating point (with tolerance)
constexpr double epsilon = 1e-9;
assert(std::abs(calculateArea(2.0) - 12.566370614) < epsilon);
// Test boolean logic
assert((true && false) == false);
assert((true || false) == true);
std::cout << "All tests passed!\n";
}
Learning Path
code
Week 1: Foundation ├── Day 1-2: Variables & data types ├── Day 3-4: Operators ├── Day 5-6: Control flow └── Day 7: Practice exercises Week 2: Functions & Arrays ├── Day 1-2: Functions basics ├── Day 3-4: Arrays & pointers ├── Day 5-6: String handling └── Day 7: Mini project
References
C++ Plugin v3.0.0 - Production-Grade Learning Skill