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Contents
  1. 1. Find a key word
  2. 2. Get a part from a string

String operation.

Find a key word

  • str.find() <cpp_ref>

    • string index starts from 0

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      std::string str("12345678901234567890");

      std::size_t found = str.find("3");
      if (found!=std::string::npos)
        std::cout << "first '3' found at: " << found << '\n';

      std::size_t found2 = str.find("3", found + 1);
      if (found2!=std::string::npos)
        std::cout << "second '3' found at: " << found2 << '\n';

      ----
      first '3' found at: 2
      second '3' found at: 12

    • find_first_of() and find_last_of()

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      found = str.find_first_of("3");
      if (found!=std::string::npos)
        std::cout << "first '3' found at: " << found << '\n';
      found = str.find_last_of("3");
      if (found!=std::string::npos)
        std::cout << "last '3' found at: " << found << '\n';

      ----
      first '3' found at: 2
      last '3' found at: 12

  • str.rfind(): find the key from right to left, at a specific position cpp_ref

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    std::string str("12345678901234567890");

    std::size_t found = str.rfind("3");
    if (found!=std::string::npos)
      std::cout << "last '3' found at: " << found << '\n';

    std::size_t found2 = str.rfind("3", found - 1);
    if (found2!=std::string::npos)
      std::cout << "second right '3' found at: " << found2 << '\n';

    found = str.rfind("3", 2);
    if (found!=std::string::npos)
      std::cout << "first '3' found at: " << found << '\n';

    ----
    last '3' found at: 12
    second right '3' found at: 2
    first '3' found at: 2

Get a part from a string

  • str.substr(pos, len) cpp_ref
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    std::string str("12345678901234567890");

    str = str.substr(3, 2);
    std::cout << str << '\n';

    ----
    45
Contents
  1. 1. Find a key word
  2. 2. Get a part from a string