error C2039: 'tolower' : is not a member of 'std'

[bomw007]

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
#include <cctype>
using std::string;
const int NUM=26;
const string wordlist[NUM]={"apiary","beetle","cereal","danger","ensign",
"florid","garage","health","insult","jackal"
,"keeper","loaner","manage","nonce","onset",
"plaid","quilt","remote","stolid","train","useful",
"valid","whence","xenon","year","zippy"};
int main()
{
using std::cout;
using std::cin;
using std::tolower;
using std::endl;
std::srand(std::time(0));
char play;
cout<<"Will you play a word game?<y/n>";
cin>>play;
play=tolower(play);
while(play=='y')
{
string target= wordlist[std::rand()%NUM];
int length=target.length();
string attempt(length,'-');
string badchars;
int guesses=6;
cout<<"Guess my secret word.it has"<<length<<"letters,and you guess\n"
<<"one letter at a time.you get"<<guesses<<"wrong guess.\n";
cout<<"your word :"<<attempt<<endl;
while(guesses>0&&attempt!=target)
{
char letter;
cout<<"guess a letter :";
cin>>letter;
if(badchars.find(letter)!=string::npos||attempt.find(letter)!=string::npos)
{
cout<<"you already guess that. Try again.\n";
continue;

}
int loc=target.find(letter);
if(loc==string::npos)
{
cout<<"oh,bad guess!\n";
badchars+=letter;
}
else
{
cout<<"Good guess!\n";
attempt[loc]=letter;
loc=target.find(letter,loc+1);
while(loc!=string::npos)
{
attempt[loc]=letter;
loc=target.find(letter,loc+1);

}
}
cout<<"your word:"<<attempt<<endl;
if(attempt!=target)
{
if(badchars.length()>0)
cout<<"bad choices:"<<badchars<<endl;
cout<<guesses<<"bad guesses left\n";

}
}
if(guesses>0)
cout<<"that is right!\n";
else
cout<<"Will you play another?<y/n>";
cin>>play;
play=tolower(play);


}
cout<<"Bye\n";
return 0;
}

------------------------------------------------------------------------------------------------------------
错误如下
C:\Program Files\Microsoft Visual Studio\MyProjects\7\7.cpp(17) : error C2039: 'tolower' : is not a member of 'std'
C:\Program Files\Microsoft Visual Studio\MyProjects\7\7.cpp(17) : error C2873: 'tolower' : symbol cannot be used in a using-declaration
C:\Program Files\Microsoft Visual Studio\MyProjects\7\7.cpp(19) : error C2039: 'srand' : is not a member of 'std'
C:\Program Files\Microsoft Visual Studio\MyProjects\7\7.cpp(19) : error C2039: 'time' : is not a member of 'std'
C:\Program Files\Microsoft Visual Studio\MyProjects\7\7.cpp(26) : error C2039: 'rand' : is not a member of 'std'

这个问题很常见了 想知道究竟是什么原因出现这样的问题，如何解决谢谢哦~~

[delphiwcdj]

参考

/* TOUPPER.C: This program uses toupper and tolower to
 * analyze all characters between 0x0 and 0x7F. It also
 * applies _toupper and _tolower to any code in this
 * range for which these functions make sense.
 */

#include <conio.h>
#include <ctype.h>
#include <string.h>

char msg[] = "Some of THESE letters are Capitals\r\n";
char *p;

void main( void )
{
   _cputs( msg );

   /* Reverse case of message. */
   for( p = msg; p < msg + strlen( msg ); p++ )
   {
      if( islower( *p ) )
         _putch( _toupper( *p ) );
      else if( isupper( *p ) )
         _putch( _tolower( *p ) );
      else
         _putch( *p );
   }
}

[bomw007]

[Quote=引用 2 楼 ddlddy 的回复:]

#include <locale>
[/Quote]

没作用

[pathuang68]

tolower不是std中的东东

[pengzhixi]

std::srand(std::time(0));
也去掉

[bomw007]

能细教么 这个不懂[Quote=引用 5 楼 delphiwcdj 的回复:]

参考
C/C++ code

/* TOUPPER.C: This program uses toupper and tolower to
* analyze all characters between 0x0 and 0x7F. It also
* applies _toupper and _tolower to any code in this
* range for which……
[/Quote]

[FrankHB1989]

[Quote=引用 7 楼 pathuang68 的回复:]

tolower不是std中的东东
[/Quote]
伸手求出处。

[书虫]

加一个
using namespace std;
不是很简洁吗？
为什么要加那么多using……

[FrankHB1989]

LZ的代码没问题，至少我VS2010能编译通过。
LZ用的标准库实现抽了。
至于去掉std::或者用<ctype.h>之类，兼容性不保证（虽然基本上都能用），看着办。

[FrankHB1989]

[Quote=引用 11 楼 happymawolf 的回复:]

加一个
using namespace std;
不是很简洁吗？
为什么要加那么多using……
[/Quote]
搜namespace pollution。
当然一个足够小的.cpp里面这么用问题不大。

[bomw007]

using namespace std；
全部释放的话可能会出现释放错误 你觉得呢[Quote=引用 11 楼 happymawolf 的回复:]

加一个
using namespace std;
不是很简洁吗？
为什么要加那么多using……
[/Quote]

[bomw007]

更改源代码如下编译无错误
int main()
{ using namespace std;
/*using std::cout;
using std::cin;
using std::tolower;
using std::endl;
std::srand(std::time(0));*/
char play;
cout<<"Will you play a word game?<y/n>";
cin>>play;
play=tolower(play);
while(play=='y')
{
string target= wordlist[/*std::*/rand()%NUM];


成功运行

[bomw007]

问题是我已经 using std::cout;
using std::cin;
using std::tolower;
using std::endl;
std::srand(std::time(0));了 怎么会爆出那样的错误呢？？？？why 不懂 ~~ 大侠教教我吧

[pengzhixi]

从c库拿来的东西，不属于C++的命名空间

[bomw007]

去了之后同样错误[Quote=引用 12 楼 frankhb1989 的回复:]

LZ的代码没问题，至少我VS2010能编译通过。
LZ用的标准库实现抽了。
至于去掉std::或者用<ctype.h>之类，兼容性不保证（虽然基本上都能用），看着办。
[/Quote]

[zhonglingqqxh]

#include <ctype>

[FrankHB1989]

[Quote=引用 17 楼 pengzhixi 的回复:]

从c库拿来的东西，不属于C++的命名空间
[/Quote]

继续伸手求出处。

[pengzhixi]

[Quote=引用 20 楼 frankhb1989 的回复:]
引用 17 楼 pengzhixi 的回复:

从c库拿来的东西，不属于C++的命名空间


继续伸手求出处。
[/Quote]
这个自己去看c++库那些ctype这样的文件

[FrankHB1989]

[Quote=引用 21 楼 pengzhixi 的回复:]

这个自己去看c++库那些ctype这样的文件
[/Quote]
ISO C++03 17.4.1.2 Headers：
4 Except as noted in clauses 18 through 27, the contents of each header cname shall be the same as that of the corresponding header name.h, as specified in ISO/IEC 9899:1990 Programming Languages C (Clause 7), or ISO/IEC:1990 Programming Languages—C AMENDMENT 1: C Integrity, (Clause 7), as appropriate, as if by inclusion. In the C++ Standard Library, however, the declarations and definitions (except for names which are defined as macros in C) are within namespace scope (3.3.5) of the namespace std.

LZ用的是<cctype>，不是<ctype.h>；ctype不是指locale的ctype cateory。
tolower这些名称应该是在std里面的。
M$在VS2010中的<cctype>：
// cctype standard header
#pragma once
#ifndef _CCTYPE_
#define _CCTYPE_
#include <yvals.h>

#ifdef _STD_USING
#undef _STD_USING
#include <ctype.h>
#define _STD_USING

#else /* _STD_USING */
#include <ctype.h>
#endif /* _STD_USING */

#if _GLOBAL_USING && !defined(RC_INVOKED)
_STD_BEGIN
using _CSTD isalnum; using _CSTD isalpha; using _CSTD iscntrl;
using _CSTD isdigit; using _CSTD isgraph; using _CSTD islower;
using _CSTD isprint; using _CSTD ispunct; using _CSTD isspace;
using _CSTD isupper; using _CSTD isxdigit; using _CSTD tolower;
using _CSTD toupper;
_STD_END
#endif /* _GLOBAL_USING */

/* remove any (improper) macro overrides */
#undef isalnum
#undef isalpha
#undef isblank
#undef iscntrl
#undef isdigit
#undef isgraph
#undef islower
#undef isprint
#undef ispunct
#undef isspace
#undef isupper
#undef isxdigit
#undef tolower
#undef toupper
#endif /* _CCTYPE_ */
在这个上下文中宏_CSTD可以是::std::，取决于编译器传给yvals.h里的设置。

[FrankHB1989]

……漏了。。
_CSTD可以是空（不使用namespace std）或::（*.h in global namespace, c* imports to std）或::std::（/* only if *.c compiled as C++ */）。

[pengzhixi]

[Quote=引用 22 楼 frankhb1989 的回复:]
引用 21 楼 pengzhixi 的回复:

这个自己去看c++库那些ctype这样的文件

ISO C++03 17.4.1.2 Headers：
4 Except as noted in clauses 18 through 27, the contents of each header cname shall be the same as that of the correspo……
[/Quote]

先赞一个，在一些老编译器，vc6.0,tc就不那么回事了。