C++ string

http://www.cplusplus.com/reference/string/string/

1. 시작 위치와 끝나는 위치

str.being()

str.end()

int main ()
{
  std::string str ("Test string");
  for ( std::string::iterator it=str.begin(); it!=str.end(); ++it)
    std::cout << *it;
  std::cout << '\n';

  return 0;
}

Output:

Test string

2. 길이(크기)

str.length()

int main ()
{
  std::string str ("Test string");
  std::cout << "The size of str is " << str.length() << " bytes.\n";
  return 0;
}

Output:

The size of str is 11 bytes

3. 한글자씩 접근

str[i]

str.at(i)

int main ()
{
  std::string str ("Test string");
  for (int i=0; i<str.length(); ++i)
  {
    std::cout << str[i];
  }
  return 0;
}

int main ()
{
  std::string str ("Test string");
  for (unsigned i=0; i<str.length(); ++i)
  {
    std::cout << str.at(i);
  }
  return 0;
}

Output:

Test string

4. 삽입(잇기)

+=

str.append()

int main ()
{
  std::string name ("John");
  std::string family ("Smith");
  name += " K. ";         // c-string
  name += family;         // string
  name += '\n';           // character

  std::cout << name;
  return 0;
}

int main ()
{
  std::string str;
  std::string str2="Writing ";
  std::string str3="print 10 and then 5 more";

  // used in the same order as described above:
  str.append(str2);                       // "Writing "
  str.append(str3,6,3);                   // "10 "
  str.append("dots are cool",5);          // "dots "
  str.append("here: ");                   // "here: "
  str.append(10u,'.');                    // ".........."
  str.append(str3.begin()+8,str3.end());  // " and then 5 more"
  str.append<int>(5,0x2E);                // "....."

  std::cout << str << '\n';
  return 0;
}

Output:

John K. Smith

Output:

Writing 10 dots here: .......... and then 5 more.....

5. 찾기

str.find()

int main ()
{
  std::string str ("There are two needles in this haystack with needles.");
  std::string str2 ("needle");

  // different member versions of find in the same order as above:
  std::size_t found = str.find(str2);
  if (found!=std::string::npos)
    std::cout << "first 'needle' found at: " << found << '\n';

  found=str.find("needles are small",found+1,6);
  if (found!=std::string::npos)
    std::cout << "second 'needle' found at: " << found << '\n';

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

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

  // let's replace the first needle:
  str.replace(str.find(str2),str2.length(),"preposition");
  std::cout << str << '\n';

  return 0;
}

Output:

first 'needle' found at: 14 second 'needle' found at: 44 'haystack' also found at: 30 Period found at: 51 There are two prepositions in this haystack with needles.

6. 부분글자

str.substr()

int main ()
{
  std::string str="We think in generalities, but we live in details.";
                                           // (quoting Alfred N. Whitehead)

  std::string str2 = str.substr (3,5);     // "think"

  std::size_t pos = str.find("live");      // position of "live" in str

  std::string str3 = str.substr (pos);     // get from "live" to the end

  std::cout << str2 << ' ' << str3 << '\n';

  return 0;
}

Output:

think live in details.

7. 비교

str.compare()

0이면 같음

int main ()
{
  std::string str1 ("green apple");
  std::string str2 ("red apple");

  if (str1.compare(str2) != 0)
    std::cout << str1 << " is not " << str2 << '\n';

  if (str1.compare(6,5,"apple") == 0)
    std::cout << "still, " << str1 << " is an apple\n";

  if (str2.compare(str2.size()-5,5,"apple") == 0)
    std::cout << "and " << str2 << " is also an apple\n";

  if (str1.compare(6,5,str2,4,5) == 0)
    std::cout << "therefore, both are apples\n";

  return 0;
}

Output:

green apple is not red apple still, green apple is an apple and red apple is also an apple therefore, both are apples