STL string 类用法总结

1.String::append与string::assign

string& append ( const string& str );
string& append ( const string& str, size_t pos, size_t n );
string& append ( const char* s, size_t n );
string& append ( const char* s );
string& append ( size_t n, char c );
template <class InputIterator>
   string& append ( InputIterator first, InputIterator last );

1)append(串,[位置],[长度])

2)append(字符数组,[长度])

3)append(个数,字符)

4)append(迭代器1,迭代器2)

2.string::at

const char& at ( size_t pos ) const;
      char& at ( size_t pos );

我们可以使用下标操作符[]和函数at()对元素包含的字符进行访问。但是应该注意的是操作符[]并不检查索引是否有效（有效索引0~str.length()），如果索引失效，会引起未定义的行为。而at()会检查，如果使用 at()的时候索引无效，会抛出out_of_range异常。 

3.string::begin

1)begin() end() //提供类似STL的迭代器支持 

string::iteratorit;it=str.begin();
2) rbegin() rend() //逆向迭代器 

string::reverse_iteratorritrit=str.rbegin();

4.与大小长度有关的函数

1)string::capacity

2)string::length

3)string::size

4)string:max_size

5.string::clear

清空字符串

6string::compare

int compare ( const string& str ) const;
int compare ( const char* s ) const;
int compare ( size_t pos1, size_t n1, const string& str ) const;
int compare ( size_t pos1, size_t n1, const char* s) const;
int compare ( size_t pos1, size_t n1, const string& str, size_t pos2, size_t n2 ) const;
int compare ( size_t pos1, size_t n1, const char* s, size_t n2) const;

1)copmare(字符数组|字符串)

2)compare(位置,长度,字符串,[位置],[长度])

3)compare(位置,长度,字符数组,[长度])

7.string::copy

可以字符串转化为字符数组

size_t copy ( char* s, size_t n, size_t pos = 0) const;

返回值是最后一个字符的位置的後一位，字符数组一般需要在最后一个位置填补'\0'

copy(字符数组，[长度]，[位置])

 int length;
  char buffer[20];
  string str ("Test string...");
  length=str.copy(buffer,6,5);
  buffer[length]='\0';

8.string::c_strstring::data

字符串转字符数组

char *cstr = new char [str.size()+1];
strcpy (cstr, str.c_str());

9.string::empty
判断字符串是否为空

10.string::erase

string& erase ( size_t pos = 0, size_t n = npos );
iterator erase ( iterator position );
iterator erase ( iterator first, iterator last );

1)erase([开始位置],[结束位置])
2)erase(迭代器1,[迭代器2])

11.string::find
size_t find ( const string& str, size_t pos = 0 ) const;
size_t find ( const char* s, size_t pos, size_t n ) const;
size_t find ( const char* s, size_t pos = 0 ) const;
size_t find ( char c, size_t pos = 0 ) const;

1)find(字符串,[位置])
2)find(字符数组,[位置],[长度])
3)find(字符,[位置])

string::rfind

size_t find ( const string& str, size_t pos = npos ) const; size_t find ( const char* s, size_t pos, size_t n ) const; size_t find ( const char* s, size_t pos = npos ) const; size_t find ( char c, size_t pos = npos ) const;

1)find(字符串,[位置])
2)find(字符数组,[位置],[长度])
3)find(字符,[位置])

12.string::insert

string& insert ( size_t pos1, const string& str ); string& insert ( size_t pos1, const string& str, size_t pos2, size_t n ); string& insert ( size_t pos1, const char* s, size_t n); string& insert ( size_t pos1, const char* s ); string& insert ( size_t pos1, size_t n, char c ); iterator insert ( iterator p, char c ); void insert ( iterator p, size_t n, char c ); template<class InputIterator> void insert ( iterator p, InputIterator first, InputIterator last );

1)insert(位置,字符串,[位置],[长度])
2)insert(位置,字符数组,[长度])
3)insert(位置,个数,字符)
4)insert(迭代器位置,[个数],字符)
5)insert(迭代器1,迭代器2)

13.string::replace

string& replace ( size_t pos1, size_t n1, const string& str );
string& replace ( iterator i1, iterator i2, const string& str );

string& replace ( size_t pos1, size_t n1, const string& str, size_t pos2, size_t n2 );

string& replace ( size_t pos1, size_t n1, const char* s, size_t n2 );
string& replace ( iterator i1, iterator i2, const char* s, size_t n2 );

string& replace ( size_t pos1, size_t n1, const char* s );
string& replace ( iterator i1, iterator i2, const char* s );

string& replace ( size_t pos1, size_t n1, size_t n2, char c );
string& replace ( iterator i1, iterator i2, size_t n2, char c );

template<class InputIterator>
   string& replace ( iterator i1, iterator i2, InputIterator j1, InputIterator j2 );

1)replace(位置,长度,字符串,[位置],[长度])：replace(迭代器1,迭代器2,字符串)
2)replace(位置,长度,字符数组,[长度]): replace(迭代器1,迭代器2,字符数组,[长度])
3)replace(位置,长度,个数,字符)：replace(迭代器1,迭代器2,个数,字符)
4)?

14.string::resize
oid resize ( size_t n, char c );
void resize ( size_t n );

Resizesthe string content to n characters.

If n issmaller than the current length of the string, the content is reducedto its first n characters, the rest being dropped.

If n isgreater than the current length of the string, the content isexpanded by appending as many instances of the c characteras needed to reach a size of n characters

15.string::substr

string substr ( size_t pos = 0, size_t n = npos ) const;
substr([位置],[长度])

16.string::swap
void swap ( string& str );