C++ std::string Complete Guide: Operations, Split, Trim & Performance

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C++ std::string Complete Guide: Operations, Split, Trim & Performance

이 글의 핵심

Hands-on reference for C++ string basics, common algorithms, pitfalls, and performance tips.

std::string is a contiguous character sequence—the same “resizable array” story as in arrays and lists.

Basics

Declaration and initialization

#include <string>
#include <iostream>
using namespace std;

string s1 = "Hello";
string s2("World");
string s3 = s1;
string s4(5, 'A');

Concatenation

Use +, +=, and append() as in the Korean article.

Comparison

==, <, and compare() for lexicographic order.

Size and access

length(), size(), operator[], at() with bounds checking.

Substrings

substr(pos, len) and substr(pos) to end.

find, rfind, find_first_of, etc.; compare position to string::npos.

Replace

replace(pos, len, new); for global substring replace, loop find + replace or use algorithms.

Insert / erase / clear

insert, erase, clear.

Practical examples

Split (CSV)

Use stringstream + getline or find / substr — patterns match the source post.

Trim

Erase from first non-space to last non-space using find_if on begin/rbegin.

Case and validation

transform with toupper/tolower; simple email / numeric checks as in original.

Common pitfalls

  1. C strings: string literals are not writable char*; use const char* or std::string.
  2. npos: use size_t / auto, not int, when comparing find results.
  3. Concatenation in loops: reserve or stringstream.

Performance

Prefer const string& parameters, reserve when size is known, and measure before low-level tricks.

FAQ

Beginner-friendly; real-world usage high; compare to other languages; learning path; common mistakes (uninitialized state, complexity, exceptions) — aligned with Korean article.

  • C++ STL vector
  • C++ set / unordered_set
  • C++ map / unordered_map

Keywords

std::string, string_view, substr, find, replace, SSO, C++, STL