ＶＳ２０１2

hywxn1 2014-04-06 04:16:38

C++primer第五版上面有一个题是从cin读入一组词并把它们存入vector对象，然后都改写成大写形式，程序段如下，用的是VS2012，可是编译错误：error C2664: “toupper”: 不能将参数 1 从“std::basic_string<_Elem,_Traits,_Alloc>”转换为“int”
这是怎么回事啊。
vector<string> v;
string word;
while(cin>>word)
{
v.push_back(word)；
}
for(auto &c:v)
c=toupper(c);

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zybjtu 2014-04-08

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for(auto &c:v) // 这个语句是遍历vector v里面的string c=toupper(c); // 这个语句是要把string 转换为大写。但是，toupper接受的是字符，不接受string。你应该一个一个转化为大写

for(auto &str : v){
      for(auto &ch : str){
             char tmp = toupper(ch);
             cout << tmp << endl;
      }
}

赵4老师 2014-04-08

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toupper _toupper, towupper Convert character to uppercase. int toupper( int c ); int _toupper( int c ); int towupper( wint_t c ); Routine Required Header Compatibility toupper <stdlib.h> and <ctype.h> ANSI, Win 95, Win NT _toupper <ctype.h> Win 95, Win NT towupper <ctype.h> or <wchar.h> ANSI, Win 95, Win NT For additional compatibility information, see Compatibility in the Introduction. Libraries LIBC.LIB Single thread static library, retail version LIBCMT.LIB Multithread static library, retail version MSVCRT.LIB Import library for MSVCRT.DLL, retail version Return Value Each of these routines converts a copy of c, if possible, and returns the result. If c is a wide character for which iswlower is true and there is a corresponding wide character for which iswupper is true, towupper returns the corresponding wide character; otherwise, towupper returns c unchanged. There is no return value reserved to indicate an error. Parameter c Character to convert Remarks Each of these routines converts a given lowercase letter to an uppercase letter if possible and appropriate. Data Conversion Routines See Also is Routines, to Functions Overview Example /* 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 ); } } Output Some of THESE letters are Capitals sOME OF these LETTERS ARE cAPITALS

hywxn1 2014-04-08

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引用 10 楼 zyaiwx 的回复:

for(auto &c:v) // 这个语句是遍历vector v里面的string c=toupper(c); // 这个语句是要把string 转换为大写。但是，toupper接受的是字符，不接受string。你应该一个一个转化为大写
for(auto &str : v){
      for(auto &ch : str){
             char tmp = toupper(ch);
             cout << tmp << endl;
      }
}

冥思苦想了两天终于弄清楚了，就是这个意思！

MRJUN00 2014-04-07