C++ Access Strings

🔎 C++ Access Strings (Characters Access Karna)

C++ mein string ke individual characters ko access (read / modify) karna bahut common hai—loops, validation, parsing, etc. ke liye.

🔹 1. Indexing Using [] Operator

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

int main() {
string name = "Sanjit";
cout << name[0]; // S
return 0;
}

👉 Index 0 se start hota hai

Index Character
0 S
1 a
2 n
3 j
4 i
5 t

🔹 2. Access Last Character

string s = "C++";
cout << s[s.length() - 1];

Output:

+

🔹 3. Using at() Function (Safe Method)

string s = "Hello";
cout << s.at(1); // e

✔ Bounds check karta hai
❌ Out of range par exception throw karta hai

🔹 4. Modify String Characters

string name = "Ram";
name[0] = 'S';
cout << name;

Output:

Sam

🔹 5. Loop Through String (Using Index)

string s = "Code";

for (int i = 0; i < s.length(); i++) {
cout << s[i] << " ";
}

Output:

C o d e

🔹 6. Range-Based For Loop (Modern C++)

string s = "C++";

for (char ch : s) {
cout << ch << " ";
}

🔹 7. Read-Only Access with const

const string s = "Hello";
cout << s[0]; // ✔ allowed
// s[0] = 'A'; // ❌ not allowed

❌ Common Mistakes

cout << s[10]; // ❌ Out of range (undefined behavior)

✔ Safe option:

cout << s.at(10); // throws error (safe)

📌 Summary

  • [] → Fast, no bounds check

  • at() → Safe, bounds check

  • Indexing starts from 0

  • Characters can be read & modified

  • Looping strings is very common

You may also like...