Home -> C++ Strings(字符串) -> 详细资料 |
string(); string( size_type length, char ch ); string( const char *str ); string( const char *str, size_type length ); string( string &str, size_type index, size_type length ); string( input_iterator start, input_iterator end ); |
字符串的构造函数创建一个新字符串,包括:
string str1( 5, 'c' ); string str2( "Now is the time..." ); string str3( str2, 11, 4 ); cout << str1 << endl; cout << str2 << endl; cout << str3 << endl;
显示
ccccc Now is the time... time
== > < >= <= != + += [] |
你可以用 ==, >, <, >=, <=, and !=比较字符串. 可以用 + 或者 += 操作符连接两个字符串, 并且可以用[]获取特定的字符.
相关主题:basic_string &append( const basic_string &str ); basic_string &append( const char *str ); basic_string &append( const basic_string &str, size_type index, size_type len ); basic_string &append( const char *str, size_type num ); basic_string &append( size_type num, char ch ); basic_string &append( input_iterator start, input_iterator end ); |
append() 函数可以完成以下工作:
string str = "Hello World"; str.append( 10, '!' ); cout << str << endl;
显示
Hello World!!!!!!!!!!相关主题:
basic_string &assign( const basic_string &str ); basic_string &assign( const char *str ); basic_string &assign( const char *str, size_type num ); basic_string &assign( const basic_string &str, size_type index, size_type len ); basic_string &assign( size_type num, char ch ); |
函数以下列方式赋值:
string str1, str2 = "War and Peace"; str1.assign( str2, 4, 3 ); cout << str1 << endl;
显示
and
reference at( size_type index ); |
at()函数返回一个引用,指向在index位置的字符. 如果index不在字符串范围内, at() 将报告"out of range"错误,并抛出out_of_range异常。 比如下列代码:
string text = "ABCDEF"; char ch = text.at( 2 );
显示字符 'C'.
相关主题:iterator begin(); |
begin()函数返回一个迭代器,指向字符串的第一个元素.
相关主题:const char *c_str(); |
c_str()函数返回一个指向正规C字符串的指针, 内容与本字符串相同.
相关主题:size_type capacity(); |
capacity()函数返回在重新申请更多的空间前字符串可以容纳的字符数. 这个数字至少与 size()一样大.
相关主题:int compare( const basic_string &str ); int compare( const char *str ); int compare( size_type index, size_type length, const basic_string &str ); int compare( size_type index, size_type length, const basic_string &str, size_type index2, size_type length2 ); int compare( size_type index, size_type length, const char *str, size_type length2 ); |
compare()函数以多种方式比较本字符串和str,返回:
返回值 | 情况 |
---|---|
小于零 | this < str |
零 | this == str |
大于零 | this > str |
不同的函数:
size_type copy( char *str, size_type num, size_type index ); |
copy()函数拷贝自己的num个字符到str中(从索引index开始)。返回值是拷贝的字符数
const char *data(); |
data()函数返回指向自己的第一个字符的指针.
相关主题:bool empty(); |
如果字符串为空则empty()返回真(true),否则返回假(false).
iterator end(); |
end()函数返回一个迭代器,指向字符串的末尾(最后一个字符的下一个位置).
相关主题:iterator erase( iterator pos ); iterator erase( iterator start, iterator end ); basic_string &erase( size_type index = 0, size_type num = npos ); |
erase()函数可以:
string s("So, you like donuts, eh? Well, have all the donuts in the world!"); cout << "The original string is '" << s << "'" << endl; s.erase( 50, 14 ); cout << "Now the string is '" << s << "'" << endl; s.erase( 24 ); cout << "Now the string is '" << s << "'" << endl; s.erase(); cout << "Now the string is '" << s << "'" << endl;
将显示
The original string is 'So, you like donuts, eh? Well, have all the donuts in the world!' Now the string is 'So, you like donuts, eh? Well, have all the donuts' Now the string is 'So, you like donuts, eh?' Now the string is ''
size_type find( const basic_string &str, size_type index ); size_type find( const char *str, size_type index ); size_type find( const char *str, size_type index, size_type length ); size_type find( char ch, size_type index ); |
find()函数:
string str1( "Alpha Beta Gamma Delta" ); unsigned int loc = str1.find( "Omega", 0 ); if( loc != string::npos ) cout << "Found Omega at " << loc << endl; else cout << "Didn't find Omega" << endl;
size_type find_first_of( const basic_string &str, size_type index = 0 ); size_type find_first_of( const char *str, size_type index = 0 ); size_type find_first_of( const char *str, size_type index, size_type num ); size_type find_first_of( char ch, size_type index = 0 ); |
find_first_of()函数:
size_type find_first_not_of( const basic_string &str, size_type index = 0 ); size_type find_first_not_of( const char *str, size_type index = 0 ); size_type find_first_not_of( const char *str, size_type index, size_type num ); size_type find_first_not_of( char ch, size_type index = 0 ); |
find_first_not_of()函数:
size_type find_last_of( const basic_string &str, size_type index = npos ); size_type find_last_of( const char *str, size_type index = npos ); size_type find_last_of( const char *str, size_type index, size_type num ); size_type find_last_of( char ch, size_type index = npos ); |
find_last_of()函数:
size_type find_last_not_of( const basic_string &str, size_type index = npos ); size_type find_last_not_of( const char *str, size_type index = npos); size_type find_last_not_of( const char *str, size_type index, size_type num ); size_type find_last_not_of( char ch, size_type index = npos ); |
find_last_not_of()函数:
allocator_type get_allocator(); |
get_allocator()函数返回本字符串的配置器.
iterator insert( iterator i, const char &ch ); basic_string &insert( size_type index, const basic_string &str ); basic_string &insert( size_type index, const char *str ); basic_string &insert( size_type index1, const basic_string &str, size_type index2, size_type num ); basic_string &insert( size_type index, const char *str, size_type num ); basic_string &insert( size_type index, size_type num, char ch ); void insert( iterator i, size_type num, const char &ch ); void insert( iterator i, iterator start, iterator end ); |
insert()函数的功能非常多:
size_type length(); |
length()函数返回字符串的长度. 这个数字应该和size()返回的数字相同.
相关主题:size_type max_size(); |
max_size()函数返回字符串能保存的最大字符数。
const reverse_iterator rbegin(); |
rbegin()返回一个逆向迭代器,指向字符串的最后一个字符。
相关主题:const reverse_iterator rend(); |
rend()函数返回一个逆向迭代器,指向字符串的开头(第一个字符的前一个位置)。
相关主题:basic_string &replace( size_type index, size_type num, const basic_string &str ); basic_string &replace( size_type index1, size_type num1, const basic_string &str, size_type index2, size_type num2 ); basic_string &replace( size_type index, size_type num, const char *str ); basic_string &replace( size_type index, size_type num1, const char *str, size_type num2 ); basic_string &replace( size_type index, size_type num1, size_type num2, char ch ); basic_string &replace( iterator start, iterator end, const basic_string &str ); basic_string &replace( iterator start, iterator end, const char *str ); basic_string &replace( iterator start, iterator end, const char *str, size_type num ); basic_string &replace( iterator start, iterator end, size_type num, char ch ); |
replace()函数:
string s = "They say he carved it himself...from a BIGGER spoon"; string s2 = "find your soul-mate, Homer."; s.replace( 32, s2.length(), s2 ); cout << s << endl;相关主题:
void reserve( size_type num ); |
reserve()函数设置本字符串的capacity 以保留num个字符空间。
相关主题:void resize( size_type num ); void resize( size_type num, char ch ); |
resize()函数改变本字符串的大小到num, 新空间的内容不确定。也可以指定用ch填充。
size_type rfind( const basic_string &str, size_type index ); size_type rfind( const char *str, size_type index ); size_type rfind( const char *str, size_type index, size_type num ); size_type rfind( char ch, size_type index ); |
rfind()函数:
int loc; string s = "My cat's breath smells like cat food."; loc = s.rfind( "breath", 8 ); cout << "The word breath is at index " << loc << endl; loc = s.rfind( "breath", 20 ); cout << "The word breath is at index " << loc << endl;相关主题:
size_type size(); |
size()函数返回字符串中现在拥有的字符数。
相关主题:basic_string substr( size_type index, size_type num = npos ); |
substr()返回本字符串的一个子串,从index开始,长num个字符。如果没有指定,将是默认值 string::npos。这样,substr()函数将简单的返回从index开始的剩余的字符串。
例如:
string s("What we have here is a failure to communicate"); string sub = s.substr(21); cout << "The original string is " << s << endl; cout << "The substring is " << sub << endl;
显示:
The original string is What we have here is a failure to communicate The substring is a failure to communicate
void swap( basic_string &str ); |
swap()函数把str和本字符串交换。例如:
string first( "This comes first" ); string second( "And this is second" ); first.swap( second ); cout << first << endl; cout << second << endl;
显示:
And this is second This comes first