C++ cin.get(s,100)与cin.getline(s,100)问题：
下面代码中用了cin.get(s,100),要2个cin.get();而用cin.getline(s,100),只需一个cin.get();
代码如下：
#include <iostream>
using namespace std;
int count(char *s,char letter)
{
int count=0;
while(*s)
if(*s++==letter)
count++;
return (count);
}
int main()
{
char str[100],c;int n;
cout<<"Please input a integer:"<<endl;
cin>>n;cin.get();
while(n--)
{
cout<<"input a string:";
cin.get(str,10);
cin.get();/*这里一个*/
cout<< "input a letter:";
cin>>c;
cout<<"the count is:"<<count(str,c)<<endl;
cin.get();/*这里又一个,才使程序正常*/
}
return 0;
}

#include <iostream>
using namespace std;
int count(char *s,char letter)
{
int count=0;
while(*s)
if(*s++==letter)
count++;
return (count);
}
int main()
{
char str[100],c;int n;
cout<<"Please input a integer:"<<endl;
cin>>n;cin.get();
while(n--)
{
cout<<"input a string:";
cin.getline(str,10);/*这里用了cin.getline(str,100),下面只需一个cin.get(),就正常了*/
cout<< "input a letter:";
cin>>c;
cout<<"the count is:"<<count(str,c)<<endl;
cin.get();
}
return 0;
}


C++
[解决办法]

      /**
       *  @brief  Simple multiple-character extraction.
       *  @param  __s  Pointer to an array.
       *  @param  __n  Maximum number of characters to store in @a s. 
 
       *  @return  *this
       *
       *  Returns @c get(__s,__n,widen('\\n')).
      */
      __istream_type&
      get(char_type* __s, streamsize __n)
      { return this->get(__s, __n, this->widen('\n')); }

      /**
       *  @brief  Extraction into another streambuf.
       *  @param  __sb  A streambuf in which to store data.
       *  @param  __delim  A "stop" character.
       *  @return  *this
       *
       *  Characters are extracted and inserted into @a __sb until one of the
       *  following happens:
       *
       *  - the input sequence reaches EOF
       *  - insertion into the output buffer fails (in this case, the
       *    character that would have been inserted is not extracted)
       *  - the next character equals @a __delim (in this case, the character
       *    is not extracted)
       *  - an exception occurs (and in this case is caught)
       *
       * If no characters are stored, failbit is set in the stream's error
       * state.
      */
      __istream_type&
      get(__streambuf_type& __sb, char_type __delim);

cin.get()有多个重载，其中两个见上面。第一种是你是用的形式，内部加上一个参数（换行符）之后调用第二种形式。
第二种形式在解释什么时候停止提取字符的时候，第三条说道：the next character equals @a __delim(in this case, the character is not extracted)。也就是说，当流中的下一个字符等于第三个参数（默认是换行符）的时候，就不再读入数据了，并且特别说明，此时，这个字符（也就是换行符）并不会被提取出来。

getline同理。

 /**
       *  @brief  String extraction.
       *  @param  __s  A character array in which to store the data.
       *  @param  __n  Maximum number of characters to extract.
       *  @param  __delim  A "stop" character.
       *  @return  *this
       *
       *  Extracts and stores characters into @a __s until one of the 
 
       *  following happens.  Note that these criteria are required to be
       *  tested in the order listed here, to allow an input line to exactly
       *  fill the @a __s array without setting failbit.
       *
       *  -# the input sequence reaches end-of-file, in which case eofbit
       *     is set in the stream error state
       *  -# the next character equals @c __delim, in which case the character
       *     is extracted (and therefore counted in @c gcount()) but not stored
       *  -# @c __n-1 characters are stored, in which case failbit is set
       *     in the stream error state
       *
       *  If no characters are extracted, failbit is set.  (An empty line of
       *  input should therefore not cause failbit to be set.)
       *
       *  In any case, a null character is stored in the next location in
       *  the array.
      */
      __istream_type&
      getline(char_type* __s, streamsize __n, char_type __delim);

      /**
       *  @brief  String extraction.
       *  @param  __s  A character array in which to store the data.
       *  @param  __n  Maximum number of characters to extract.
       *  @return  *this
       *
       *  Returns @c getline(__s,__n,widen('\\n')).
      */
      __istream_type&
      getline(char_type* __s, streamsize __n)
      { return this->getline(__s, __n, this->widen('\n')); }

下面的形式加上一个参数（换行符）之后调用上面的形式。上面形式第二条注释说：the next character equals @c __delim, in which case the character is extracted (and therefore counted in @c gcount()) but not stored。意思是，当下一个字符等于第三个参数的时候就不再提取数据，此时，这个字符（换行符）会被读出并且会被gcount()函数统计，但是并不存储到参数中。

因此呢，这两者的区别就在于行尾的换行符而已。get(str, 10)不读取换行符，所以需要一个额外的get()读取并抛弃之。而getline(str, 10)形式默认就读取了换行符，所以可以少一个get()。最后那个get()两种情况都是需要的，因为输入letter之后还多的一个换行符还存在流中呢，需要抛弃。