编译错误消息

可能重复：
Boolean and Void problem 编译错误消息

所以我有此代码具有求和n个元素的向量

C++语法的总和函数（切换平原Text）

#include <iostream> 
#include <vector> // need this in order to use vectors in the program 
using namespace std; 


void computeSum (vector<int> &Vec, int howMany, int total, bool success) 
    //the computeSum function that will sum positive numbers in a vector 
{ 
    int j; 
    total=0; 
    for(j=0;j < howMany;j++) 
     if (Vec[j] > 0){ 
      total+=Vec[j]; 
     } else { 
      total+=Vec[j+1]; 
     } 
    if (howMany > Vec[j]) 
     success = false; 
    else 
     success = true; 
    if (total != 0) 
     success = true; 
    if (success=true){ 
     cout << total; 
    } else { 
     cout << "Oops! Appears you cannot add up these numbers!"; 
    } 

} 

int main() 
{ 
    vector<int> dataVec; 
    bool success; 
    int i, n, howMany, total; 
    cout << "How many numbers would you like to put into the vector? \n"; 
    cin >> n; 

    dataVec.resize(n); 

    for(vector<int>::size_type i=0;i < n;i++) 
    { 
     cout << "Enter your number for " << i+1 << ": \n"; 
     cin >> dataVec[i]; 
    } 

    cout << "How many POSITIVE numbers would you like to sum? \n"; 
    cin >> howMany; 
    cout << "Your total is " << computeSum(dataVec, howMany, total, success); 
}

现在我加入前的

C++语法（切换纯文本）

bool success;

主

（） - 我唯一的错误是成功不在主声明 - 所以现在我宣布它和我得到这个...

g++ -I/usr/local/include/bjarne/GUI -I -Wall -O3 -DNDEBUG -Wno-deprecated proj1.cc -o proj1 
proj1.cc: In function ‘int main()’: 
proj1.cc:59:76: error: no match for ‘operator<<’ in ‘std::operator<< [with _Traits = std::char_traits<char>]((* & std::cout), ((const char*)"Your total is ")) << computeSum((* & dataVec), howMany, total, ((int)success))’ 
proj1.cc:59:76: note: candidates are: 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:110:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:110:7: note: no known conversion for argument 1 from ‘void’ to ‘std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&)’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:119:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>, std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:119:7: note: no known conversion for argument 1 from ‘void’ to ‘std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&)’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:129:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:129:7: note: no known conversion for argument 1 from ‘void’ to ‘std::ios_base& (*)(std::ios_base&)’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:167:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:167:7: note: no known conversion for argument 1 from ‘void’ to ‘long int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:171:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:171:7: note: no known conversion for argument 1 from ‘void’ to ‘long unsigned int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:175:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:175:7: note: no known conversion for argument 1 from ‘void’ to ‘bool’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:93:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:93:5: note: no known conversion for argument 1 from ‘void’ to ‘short int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:182:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:182:7: note: no known conversion for argument 1 from ‘void’ to ‘short unsigned int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:107:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:107:5: note: no known conversion for argument 1 from ‘void’ to ‘int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:193:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:193:7: note: no known conversion for argument 1 from ‘void’ to ‘unsigned int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:202:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:202:7: note: no known conversion for argument 1 from ‘void’ to ‘long long int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:206:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:206:7: note: no known conversion for argument 1 from ‘void’ to ‘long long unsigned int’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:211:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:211:7: note: no known conversion for argument 1 from ‘void’ to ‘double’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:215:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:215:7: note: no known conversion for argument 1 from ‘void’ to ‘float’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:223:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:223:7: note: no known conversion for argument 1 from ‘void’ to ‘long double’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:227:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:227:7: note: no known conversion for argument 1 from ‘void’ to ‘const void*’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:121:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>] 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:121:5: note: no known conversion for argument 1 from ‘void’ to ‘std::basic_ostream<char>::__streambuf_type*’ 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/basic_string.h:2694:59: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:451:65: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:456:63: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:462:61: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:468:68: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:473:70: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:493:72: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:323:70: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:510:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:523:75: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*) 
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:528:77: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*) 
make: *** [proj1] Error 1

....什么？

**我甚至在加的主要INT结束返回（（返程0;）），并且仍然我得到的错误上午

来源

2011-09-19 Clam

不要再问同样的问题了。 –

您正在尝试cout的computeSum返回值是void。你不能cout << void。

/* computeSum returns void! */ 
cout << "Your total is " << computeSum(dataVec, howMany, total, success);

来源

2011-09-19 10:49:05 cnicutar

该方案有很多问题，事实证明。我试图掩盖一切，但我可能错过了一些。而且因为我说了很长时间。

给你错误信息的问题是使用computeSum（）的返回类型。现在，computeSum（）的返回类型是无效的（即它不会返回任何东西），但是在发生错误的行中，您试图打印由computeSum（）返回的任何内容。

在我看来，你想'total'由computeSum（）返回，而不是作为参数给出。要做到这一点，而不是让“总”的参数的computeSum（）开始宣布它，并在函数的最末尾添加一行

return total;

所以computeSum（）应该是这样的：

int computeSum(vector<int> &Vec, int howMany, bool success) 
{ 
    int total = 0; 

    //... 

    return total; 
}

还有与加起来部分中的逻辑错误 - 想，当有一排例如两个负数会发生什么。

这里是一个更好的版本：

int total = 0; 
int i = 0;   //the index of the current item being looked at 
int numAddedUp = 0; //the number of positive numbers seen 

//loop while need to add up more numbers AND i is within the bounds of Vect 
//so stop upon reaching end of Vect even if not added up 'howMany' items yet. 
while (numAdded < howMany && i < Vect.size()) 
{ 
    if (Vect[i] > 0) 
    { 
     //if it's positive, add it 
     total += Vect[i]; 
     numAddedUp++; 
    } 
    i++; 
}

的 '成功' 的逻辑似乎站不住脚给我。如果使用while循环，我建议，你可以使用它代替：

if (numAddedUp == howMany) 
{ 
    success = true; 
} 
else 
{ 
    success = false; 
}

或者更简单地，

success = (numAddedUp == howMany);

你可以用于检测特殊情况下延长了检查，例如当的howmany小于一。下面的行会检查的howmany是有效的，添加了比赛的项目数的howmany：

success = (howMany >= 1) && (numAddedUp == howMany);

同样注意线

if (success=true){

其为分配（=）值true到'成功'，但你想要做的是检查是否相等（==）。

最后，想想你打印输出的方式。现在main（）和computeSum（）都是打印的东西。理想情况下，computeSum（）不会打印任何内容，并且总数将随bool指示成功/失败一起返回。然而，更容易（但不是很好的做法）方法是让computeSum（）打印输出，甚至不打扰返回任何东西。主（）方法将只是必须调用这样的功能：

computeSum(dataVec, howMany);

作为输出将在computeSum（）与漂亮的，详细的，用户友好的错误消息，如沿着打印“的程序是不工作，和它一起生活。“或“你破坏了程序！”。

来源

2011-09-19 12:44:04 tom

编译错误消息

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