下面的代碼,是一位同學為《[初識對象](http://blog.csdn.net/sxhelijian/article/details/44116231)》中的[項目3時間類](http://blog.csdn.net/sxhelijian/article/details/44116309)寫的。但錯誤有點詭異,他在QQ群中求助。
~~~
#include <iostream>
using namespace std;
class Time
{
public:
void set_time();
void show_time();
void add_sec(int);
void add_minute(int);
void add_hour(int);
void add_a_sec()
{
sec=sec+1;
if(sec==60)
{
sec=0;
minute=minute+1;
if(minute==60)
{
minute=0;
hour=hour+1;
}
}
void add_a_minute()
{
minute=minute+1;
if(minute==60)
{
minute=0;
hour=hour+1;
}
}
void add_an_hour()
{
hour=hour+1;
}
private:
bool is_time(int, int, int); //這個成員函數設置為私有的,是合適的,請品味
int hour;
int minute;
int sec;
};
void Time::set_time()
{
char c1,c2;
cout<<"請輸入時間(格式hh:mm:ss)";
while(1)
{ cin>>hour>>c1>>minute>>c2>>sec;
if(c1!=':'||c2!=':')
cout<<"格式不正確,請重新輸入"<<endl;
else if (!is_time(hour,minute,sec))
cout<<"時間非法,請重新輸入"<<endl;
else
break;
}
}
void Time::show_time()
{
cout<<hour<<":"<<minute<<":"<<sec<<endl;
}
bool Time::is_time(int h,int m, int s)
{
if (h<0 ||h>24 || m<0 ||m>60 || s<0 ||s>60)
return false;
return true;
}
void Time::add_sec(int adds)
{
sec=sec+adds;
while(sec>=60)
{
sec=sec-60;
minute=minute+1;
if(minute==60)
{
minute=0;
hour=hour+1;
}
}
}
void Time::add_minute(int addm)
{
minute=minute+addm;
while(minute>=60)
{
minute=minute-60;
hour=hour+1;
}
}
void Time::add_hour(int addh)
{
hour=hour+addh;
}
int main( )
{
Time t1;
int adds,addm,addh;
cout<<"請輸入要增加的秒,分,小時"<<endl;
cin>>adds>>addm>>addh;
t1.set_time( );
T1.show_time( );
t1.add_a_sec();
t1.add_a_minute();
t1.add_an_hour();
t1.add_sec(adds);
t1.add_minute(adds);
t1.add_hour(addh);
return 0;
}
~~~
讀者朋友,你編譯一下試試?
我在CodeBlocks中編譯,提示一大堆:
~~~
||=== Build: Debug in example (compiler: GNU GCC Compiler) ===|
D:\CPP\codeBlock\example\main.cpp|43|error: extra qualification 'Time::' on member 'set_time' [-fpermissive]|
D:\CPP\codeBlock\example\main.cpp|43|error: 'void Time::set_time()' cannot be overloaded|
D:\CPP\codeBlock\example\main.cpp|6|error: with 'void Time::set_time()'|
D:\CPP\codeBlock\example\main.cpp|57|error: extra qualification 'Time::' on member 'show_time' [-fpermissive]|
D:\CPP\codeBlock\example\main.cpp|57|error: 'void Time::show_time()' cannot be overloaded|
D:\CPP\codeBlock\example\main.cpp|7|error: with 'void Time::show_time()'|
D:\CPP\codeBlock\example\main.cpp|61|error: extra qualification 'Time::' on member 'is_time' [-fpermissive]|
D:\CPP\codeBlock\example\main.cpp|67|error: extra qualification 'Time::' on member 'add_sec' [-fpermissive]|
D:\CPP\codeBlock\example\main.cpp|67|error: 'void Time::add_sec(int)' cannot be overloaded|
D:\CPP\codeBlock\example\main.cpp|8|error: with 'void Time::add_sec(int)'|
D:\CPP\codeBlock\example\main.cpp|81|error: extra qualification 'Time::' on member 'add_minute' [-fpermissive]|
D:\CPP\codeBlock\example\main.cpp|81|error: 'void Time::add_minute(int)' cannot be overloaded|
D:\CPP\codeBlock\example\main.cpp|9|error: with 'void Time::add_minute(int)'|
D:\CPP\codeBlock\example\main.cpp|90|error: extra qualification 'Time::' on member 'add_hour' [-fpermissive]|
D:\CPP\codeBlock\example\main.cpp|90|error: 'void Time::add_hour(int)' cannot be overloaded|
D:\CPP\codeBlock\example\main.cpp|10|error: with 'void Time::add_hour(int)'|
D:\CPP\codeBlock\example\main.cpp|109|error: expected '}' at end of input|
D:\CPP\codeBlock\example\main.cpp||In member function 'void Time::add_a_sec()':|
D:\CPP\codeBlock\example\main.cpp|13|error: 'sec' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|17|error: 'minute' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|21|error: 'hour' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|25|error: a function-definition is not allowed here before '{' token|
D:\CPP\codeBlock\example\main.cpp|42|error: expected '}' at end of input|
D:\CPP\codeBlock\example\main.cpp||In member function 'void Time::set_time()':|
D:\CPP\codeBlock\example\main.cpp|48|error: 'hour' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|48|error: 'minute' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|48|error: 'sec' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp||In member function 'void Time::show_time()':|
D:\CPP\codeBlock\example\main.cpp|59|error: 'hour' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|59|error: 'minute' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|59|error: 'sec' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp||In member function 'void Time::add_sec(int)':|
D:\CPP\codeBlock\example\main.cpp|69|error: 'sec' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|73|error: 'minute' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|77|error: 'hour' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp||In member function 'void Time::add_minute(int)':|
D:\CPP\codeBlock\example\main.cpp|83|error: 'minute' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|87|error: 'hour' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp||In member function 'void Time::add_hour(int)':|
D:\CPP\codeBlock\example\main.cpp|92|error: 'hour' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp||In member function 'int Time::main()':|
D:\CPP\codeBlock\example\main.cpp|101|error: 'T1' was not declared in this scope|
D:\CPP\codeBlock\example\main.cpp|103|error: 'class Time' has no member named 'add_a_minute'|
D:\CPP\codeBlock\example\main.cpp|104|error: 'class Time' has no member named 'add_an_hour'|
D:\CPP\codeBlock\example\main.cpp|109|error: expected unqualified-id at end of input|
||=== Build failed: 38 error(s), 0 warning(s) (0 minute(s), 1 second(s)) ===|
~~~
第一個提示“extra qualification 'Time::' on member 'set_time'”,說Time::多余,類外定義成員函數,不多余啊!
第二個提示“ 'void Time::set_time()' cannot be overloaded”,Time::set_time()不能被重載。
我大概知道怎么回事了。
用resource code formatter整理程序的格式,縮進發生變化,妖孽立刻現身。
下面是我和學生在QQ群中的對話,讀者如果沒有找出錯誤,不妨邊看邊試,按我的提示,自己找出問題來。
賀老師 2015-3-21 18:54:18
在Code::Blocks中,你整理一下格式,你會知道這個錯有多么低級。然后回頭再看這些錯誤提示,可以引出不少有價值的東西來。
賀老師 2015-3-21 18:55:28
其他同學,也可以從XX的低級錯誤中學到不少,試試吧。
學生 2015-3-21 18:57:37
糗大了
賀老師 2015-3-21 18:59:26
這樣的錯誤,在學習過程中,價值連城!你經過了這樣的錯誤,你就擁有了特別的財富。
學生 2015-3-21 19:00:37
還是有一點不大明白
賀老師 2015-3-21 19:01:13
重排版了嗎?
學生 2015-3-21 19:01:25
排了
賀老師 2015-3-21 19:01:34
你能確認void Time::set_time()是在類外了嗎?
學生 2015-3-21 19:02:37
嗯 ?類內定義 ?類外寫函數
賀老師 2015-3-21 19:03:06
如果類外定義,這個函數該頂頭才是,
賀老師 2015-3-21 19:03:19
類內定義,才會縮進去。
賀老師 2015-3-21 19:03:46
你類內聲明,類內定義。
賀老師 2015-3-21 19:04:22
這就重復了。
賀老師 2015-3-21 19:07:50
發現了嗎?要不要再給點線索?
學生 2015-3-21 19:08:34
在給點吧?
賀老師 2015-3-21 19:09:07
你看類內定義的void add_a_sec(),在哪兒結束的?
學生 2015-3-21 19:10:09
落了一個括號
賀老師 2015-3-21 19:10:26
手邊有磚嗎?
學生 2015-3-21 19:10:54
不是 是括號括錯了 ? 我去買塊豆腐磚
學生 2015-3-21 19:11:45
謝謝賀老 ? ?
賀老師 2015-3-21 19:11:48
沒磚為師就放心了。不必拍,我怕豆腐疼。學習過程中,很正常。
賀老師 2015-3-21 19:12:40
以后錯誤莫名其妙時,可以排版一下。若縮進不正常,問題一下就出來了。這也是講究規范的價值。
學生 2015-3-21 19:13:00
恩恩 學到了