C++ string 类的 find 方法实例详解

1、C++ 中 string 类的 find 方法列表

size_type std::basic_string::find(const basic_string &__str, size_type __pos);
size_type std::basic_string::find(const _CharT *__s, size_type __pos, size_type __n);
size_type std::basic_string::find(const _CharT *__s, size_type __pos);
size_type std::basic_string::find(_CharT __c, size_type __pos);

size_type std::basic_string::rfind(const basic_string &__str, size_type __pos);
size_type std::basic_string::rfind(const _CharT *__s, size_type __pos, size_type __n);
size_type std::basic_string::rfind(const _CharT *__s, size_type __pos);
size_type std::basic_string::rfind(_CharT __c, size_type __pos);

size_type std::basic_string::find_first_of(const basic_string &__str, size_type __pos);
size_type std::basic_string::find_first_of(const _CharT *__s, size_type __pos, size_type __n);
size_type std::basic_string::find_first_of(const _CharT *__s, size_type __pos);
size_type std::basic_string::find_first_of(_CharT __c, size_type __pos);

size_type std::basic_string::find_last_of(const basic_string &__str, size_type __pos);
size_type std::basic_string::find_last_of(const _CharT *__s, size_type __pos, size_type __n);
size_type std::basic_string::find_last_of(const _CharT *__s, size_type __pos);
size_type std::basic_string::find_last_of(_CharT __c, size_type __pos);

size_type std::basic_string::find_first_not_of(const basic_string &__str, size_type __pos);
size_type std::basic_string::find_first_not_of(const _CharT *__s, size_type __pos, size_type __n);
size_type std::basic_string::find_first_not_of(const _CharT *__s, size_type __pos);
size_type std::basic_string::find_first_not_of(_CharT __c, size_type __pos);

size_type std::basic_string::find_last_not_of(const basic_string &__str, size_type __pos);
size_type std::basic_string::find_last_not_of(const _CharT *__s, size_type __pos, size_type __n);
size_type std::basic_string::find_last_not_of(const _CharT *__s, size_type __pos);
size_type std::basic_string::find_last_not_of(_CharT __c, size_type __pos);

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 本文以代码和运行实例进行解析，实例中的颜色部分的规则如下：

黄色底色：在原字符串中经过了搜索，没有黄色底色的表示不在我们的搜索范围内

红色字体：搜索错误的地方

绿色字体：搜索正确

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下面逐个解析

　　find()、

　　rfind()、

　　find_first_of()、

　　find_last_of()、

　　find_first_not_of()、

　　find_last_not_of()

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2、find()

　　find函数在C++的头文件basic_string.h中有四种定义，定义如下：　

　　2.1）第一个定义：size_type find(const _CharT* __s, size_type __pos, size_type __n) const;

       /**
       *  @brief  Find position of a C substring.
       *  @param __s  C string to locate.
       *  @param __pos  Index of character to search from.
       *  @param __n  Number of characters from @a s to search for.
       *  @return  Index of start of first occurrence.
       *
       *  Starting from @a __pos, searches forward for the first @a
       *  __n characters in @a __s within this string.  If found,
       *  returns the index where it begins.  If not found, returns
       *  npos.
      */
      size_type
      find(const _CharT* __s, size_type __pos, size_type __n) const;

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