Error no matching function for call to find

Problem

Today, I got a rather weird C++ error. That is. My code is very simply doing a search using the std::find() function as follow:

    auto it(std::find(
          headers.cbegin()
        , headers.cend()
        , column_name));

Yet, it would not compile that simple line of  code.

Clearly, I use the begin() and end() of the same vector, and I use a value which is exactly what the vector is made of (we see that in the first line of error below: the std::vector<> T parameter is a basic string, which is what column_name is.)

Looking at the error, we see that it says that it’s just not compatible. It expects an std::istreambuf_iterator. Why would C++ tell me that such a type is required when I used a parameter to the function which is an std::vector.

[  5%] Building CXX object src/CMakeFiles/addr.dir/route.cpp.o
/home/snapwebsites/snapcpp/contrib/libaddr/src/route.cpp: In function ‘int addr::{anonymous}::get_position(const words_t&, const string&)’:
/home/snapwebsites/snapcpp/contrib/libaddr/src/route.cpp:113:22: error: no matching function for call to ‘find(std::vector<std::__cxx11::basic_string<char> >::const_iterator, std::vector<std::__cxx11::basic_string<char> >::const_iterator, const string&)’
         , column_name));
                      ^
In file included from /usr/include/c++/5/bits/locale_facets.h:48:0,
                 from /usr/include/c++/5/bits/basic_ios.h:37,
                 from /usr/include/c++/5/ios:44,
                 from /usr/include/c++/5/istream:38,
                 from /usr/include/c++/5/fstream:38,
                 from /home/snapwebsites/snapcpp/contrib/libaddr/src/route.cpp:41:
/usr/include/c++/5/bits/streambuf_iterator.h:369:5: note: candidate: template<class _CharT2> typename __gnu_cxx::__enable_if<std::__is_char<_CharT2>::__value, std::istreambuf_iterator<_CharT> >::__type std::find(std::istreambuf_iterator<_CharT>, std::istreambuf_iterator<_CharT>, const _CharT2&)
     find(istreambuf_iterator<_CharT> __first,
     ^
/usr/include/c++/5/bits/streambuf_iterator.h:369:5: note:   template argument deduction/substitution failed:
/home/snapwebsites/snapcpp/contrib/libaddr/src/route.cpp:113:22: note:   ‘__gnu_cxx::__normal_iterator<const std::__cxx11::basic_string<char>*, std::vector<std::__cxx11::basic_string<char> > >’ is not derived from ‘std::istreambuf_iterator<_CharT>’
         , column_name));
                      ^
src/CMakeFiles/addr.dir/build.make:158: recipe for target 'src/CMakeFiles/addr.dir/route.cpp.o' failed

If you think that this error is not talkative, welcome to the club! It took me a moment to find the reason for the problem…

Solution

The fact is that this problem is caused by the missing definition of the default std::find() function. What was needed in that C++ file was a #include of the algorithms. The following:

#include <algorithm>

In fact, I had the input stream included, so the following:

#include <ifstream>

And it looks like they have a specialization of the std::find() algorithm for one to search through it stream buffer. That definition gets picked up if you have only that one include.

By adding the other include, now C++ is capable of finding a matching std::find() and compiles my file happily.

If you’re interested about finding the list of routes on your Linux OS using a C++ class, I have that in my libaddr library.

У меня есть следующий код:

#include <algorithm>
#include <vector>
#include <iostream>
#include <stdio.h>

using namespace std;

int main()
{   
    typedef vector<int> IntContainer;
    typedef IntContainer::iterator IntIterator;

    IntContainer vw;

    IntIterator i = find(vw.begin(), vw.end(), 5);

    if (i != vw.end()) 
        {
        printf("Find 5 in vectorn");   // found it
      }
        else 
        {
            printf("Couldn't find 5 in vectorn");  // couldn't found it
        }

    return 0;
}

Я пытаюсь скомпилировать его в Ubuntu с помощью gcc 4.7.1 и получаю следующую ошибку:

vec_test.cpp: In function ‘int main()’:
vec_test.cpp:27:46: error: no matching function for call to ‘find(std::vector<int>::iterator, std::vector<int>::iterator, int)’
vec_test.cpp:27:46: note: candidate is:
In file included from /usr/local/lib/gcc/i686-pc-linux-gnu/4.7.1/../../../../include/c++/4.7.1/bits/locale_facets.h:50:0,
                 from /usr/local/lib/gcc/i686-pc-linux-gnu/4.7.1/../../../../include/c++/4.7.1/bits/basic_ios.h:39,
                 from /usr/local/lib/gcc/i686-pc-linux-gnu/4.7.1/../../../../include/c++/4.7.1/ios:45,
                 from /usr/local/lib/gcc/i686-pc-linux-gnu/4.7.1/../../../../include/c++/4.7.1/ostream:40,
                 from /usr/local/lib/gcc/i686-pc-linux-gnu/4.7.1/../../../../include/c++/4.7.1/iostream:40,
                 from vec_test.cpp:3:
/usr/local/lib/gcc/i686-pc-linux-gnu/4.7.1/../../../../include/c++/4.7.1/bits/streambuf_iterator.h:371:5: note: template<class _CharT2> typename __gnu_cxx::__enable_if<std::__is_char<_CharT2>::__value, std::istreambuf_iterator<_CharT2, std::char_traits<_CharT> > >::__type std::find(std::istreambuf_iterator<_CharT2, std::char_traits<_CharT> >, std::istreambuf_iterator<_CharT2, std::char_traits<_CharT> >, const _CharT2&)
/usr/local/lib/gcc/i686-pc-linux-gnu/4.7.1/../../../../include/c++/4.7.1/bits/streambuf_iterator.h:371:5: note:   template argument deduction/substitution failed:
vec_test.cpp:27:46: note:   ‘__gnu_cxx::__normal_iterator<int*, std::vector<int> >’ is not derived from ‘std::istreambuf_iterator<_CharT2, std::char_traits<_CharT> >’

Этот код ничего не делает, так как вектор не инициализируется каким-либо содержимым, но он должен компилироваться.

Я подозреваю, что это проблема gcc, но после долгих копаний я совсем отчаялся. Подскажите, пожалуйста, если кто-то сталкивался с этой проблемой и знает, как ее решить.

1

26.01.2016, 23:20. Показов 10952. Ответов 3

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#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>
 
struct edge {
    int one;
    int two;
    double mass;
};
 
bool comp(edge one, edge two) {
    return one.mass > two.mass;
};
 
class DSofNude {    
private:
    int amount_of_nudes; 
    std::vector<int> nudes;
    
    void UniteFathers(int one, int two);
    
public:
    DSofNude(int value);
    int Find(int son);
    void Unite(int one, int two);
    bool IsDSIsOne();
};
 
class Graph {
public:
    Graph(int value, std::vector<edge> edgess);
    double FindAnswer();
    
private:
    int amount_of_nodes;
    std::vector<edge> edges;
    DSofNude DSnudes;
    
    double FindAnswerInCout(std::vector<edge>::iterator begin,
     std::vector<edge>::iterator end);
    bool IsGraphCorect(std::vector<edge>::iterator begin,
     std::vector<edge>::iterator end);
};
 
int main() {
    int nudes, edg;
    std::cin >> nudes >> edg;
    
    std::vector<edge> edges;
    edge example;
    for(int i = 0; i < edg; ++i) {
        std::cin >> example.one >> example.two >> example.mass;
        edges.push_back(example);
    }
    
    Graph graph = Graph(nudes, edges);
    std::cout << graph.FindAnswer();
    return 0;
}
 
DSofNude::DSofNude(int value) {
    amount_of_nudes = value;
    for(int i = 0; i < amount_of_nudes; ++i) {
        nudes.push_back(i);
    }
}
 
int DSofNude::Find(int son) {
    int father = son;
    while(father != nudes[father]) {
        father = nudes[father];
    }
    nudes[son] = father;
    
    return father;
}
 
void DSofNude::Unite(int one, int two) {
    UniteFathers(Find(one), Find(two));
}
 
bool DSofNude::IsDSIsOne() {
    int set = Find(0);
    for(int i = 1; i < amount_of_nudes; ++i) {
        if (set != Find(i)) {
            return false;
        }
    }
    
    return true;
}
 
void DSofNude::UniteFathers(int one, int two) {
    nudes[one] = two;
}
 
Graph::Graph(int value, std::vector<edge> edgess) {
    DSnudes = DSofNude(value);
    amount_of_nodes = value;
    edges = edgess;
}
 
double Graph::FindAnswer() {
    std::sort(edges.begin(), edges.end(), comp);
    return FindAnswerInCout(edges.begin(), edges.end());
}
 
double Graph::FindAnswerInCout(std::vector<edge>::iterator begin,
 std::vector<edge>::iterator end) {
    if (begin + 1 == end) { 
        if (IsGraphCorect(begin, end)) {
            return  begin->mass;
        } else {
            return -1; 
        }
    }
    
    std::vector<edge>::iterator mediana = begin + (end - begin) / 2;
    if (IsGraphCorect(begin, mediana)) {
        return FindAnswerInCout(begin, mediana);
    } else {
        return FindAnswerInCout(mediana, end);
    }
}
 
bool Graph::IsGraphCorect(std::vector<edge>::iterator begin,
std::vector<edge>::iterator end) {
    DSofNude ds = DSnudes;
    while(begin < end) {
        ds.Unite(begin->one, begin->two);
        ++begin;
    }
    
    bool answer = ds.IsDSIsOne();
    if (!answer) {
        DSnudes = ds;  
    }
    return answer;
}

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The no matching function for call to C++ constructor error appears when the identification of the called process does not match the argument. For instance, whenever the compiler specifies no matching functions or methods exist, it indicates the compiler identified a function by an exact name in the command’s parameter.

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Why Is the No Matching Function for Call to C++ Bug Happening?

The C++ no matching function for call to default constructor error happens and affects your programming experience when the identification of the called process does not match the argument. As a result, this error indicates the system cannot recognize the data type in your document due to identical names.

So, the no matching function for call to Arduino mistake can obliterate your program if you introduce many properties with identical ids. Consequently, the system will fail to read the adequate role, confusing developers about why and where the script launches exceptions, although all elements appear functional.

In addition, unfortunately, this creates unexpected obstacles because sometimes scanning the complete code will be essential to remove the no matching function for call to printf bug. However, we are far from discussing the possible debugging methods because you must learn how to recreate the full invalid exception and output.

So, the message is almost inevitable when we continue to pass the specific incorrect method or wrong parameter set to the function. The program will launch the no matching function for call to max C++ error because the function’s definition specifies the method’s name to the compiler.

In addition, your script explicitly declares the entire broken function or command content. As a result, having identical ids for several properties confuses your application and blocks further procedures launched by the incorrect command.

– Creating Public Classes in the Main Function

You will likely experience the no matching function for call to ‘stoi mistake when creating public classes in the primary function using typical elements. Unfortunately, as explained before, the syntax includes a few ids that provoke the system to launch the error.

You can learn more about the primary function and properties in the following example:

Although the tags and values appear correct, your system displays an exception indicating the broken functions. The following example provides the absolute error:

Unfortunately, the error can happen if your code calls specific commands with invalid parameters.

– Calling Commands With Invalid Parameters

Your system can sometimes prevent you from completing the code when your script calls several commands with invalid parameters.

Although this happens rarely, it can produce unexpected mistakes, especially with complex applications with many procedures. Therefore, we will show you a syntax that blocks the main function and halts further processes.

The following example provides the broken code:

After running the command and launching the properties, your system will display the following error:

This script calls the shuffle command with a failed parameter, which blocks further operations.

– Failing To Read the Standard Halts All Procedures

This article’s last invalid chapter recreates the matching function error in C++ and fails to read the standard, which halts all processes. Unfortunately, predicting when and where this happens is almost impossible, especially if you have a script with many operations and elements.

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The following example provides the script that fails to read the standard:

Although appearing insignificant, the incorrect message indicates inconsistencies. Learn more about the message below:

This example completes our guide on recreating the mistake, so it is time to apply the most sophisticated debugging approaches.

How To Resolve the No Matching Function for Call to C++ Mistake?

You can resolve the no matching function for call to C++ error by providing corresponding and functional parameters to the broken function. In addition, you can quickly obliterate the bugged message by introducing different parameters for the various overloaded functions. Luckily, both approaches will not affect secondary processes and elements.

In addition, you can remove this error by changing the code to meet the command’s expectations. This procedure ensures your template has fair inputs the system can render effortlessly.

But first, let us simplify the script, as shown below:

Furthermore, as explained before, you can modify the properties to meet the function’s needs. The following example provides the best approach:

As you can tell, this method repairs this article’s last chapter that recreates the bug. Luckily, you can apply it to all documents and applications.

– Repair the Compiler Defaults

The second debugging approach fixes the compiler defaults that confuse your system. Follow the steps in this bullet list to delete the code exception:

• Choose Compiler Options in the tool menu.
• Select the Settings tab that appears in the pop-up windows.
• Locate and choose Code Generation in the next tab.
• Click on the arrow on the right on the Language Standard line.
• Choose ISO C++ 11 from the list box and press OK.

The mistake should disappear, and you can complete the project without further complications or errors.

Conclusion

The no-matching function for the call in C++ error appears when the identification of the called process does not match the argument. As a result, we explained the following critical points to help you debug the code:

• Checking the parameters of the required methods and their data type is critical
• We usually make mistakes when writing the arguments in the functions
• You can allow the process by providing the matched parameter
• Adding a new role in the exact data type set should remove the mistake

We are confident that you will no longer experience this annoying exception after applying these debugging principles. Luckily, the methods apply to similar matching function errors.