C++ compilation error: Invalid function argument cannot be used, how to solve it?

In C programming, compilation errors are a very common thing, which is also a problem we must face in the process of learning and using C. One of the common compilation errors is "cannot use invalid function argument", which often occurs when writing functions. This article will introduce the cause and solution of this compilation error.

1. Error reason

Compilation error "Cannot use invalid function argument" is usually caused by using incorrect parameter type or number. Specifically, this error is usually caused by the following reasons:

1.1 Parameter type mismatch

C When defining a function, you need to specify the type of the parameter. If the parameter type is passed in when calling the function Mismatching parameter types will result in compilation errors. For example, if we define a function as follows:

void print(int n) {
    std::cout << n << std::endl;
}

When calling this function, if the parameter type passed in is not int, a compilation error will occur, for example:

double x = 3.14;
print(x); // 错误，参数类型不匹配

1.2 Number of parameters Mismatch

On the other hand, if the number of parameters passed to the function is illegal, a compilation error will also occur, for example:

void print(int n) {
    std::cout << n << std::endl;
}

When calling this function, if the number of parameters passed in is not 1 , a compilation error will occur, for example:

int a = 1, b = 2;
print(a, b); // 错误，参数数量不匹配

2. Solution

One advantage of the compilation error "Cannot use invalid function argument" is that it tells us that in the function call Something went wrong. As long as we know the specific cause of the error, we can take appropriate measures to solve the problem.

2.1 Confirm whether the parameter types match

If a compilation error "Cannot use invalid function arguments" occurs, we should first confirm the type of the parameters in the function definition and the parameters passed in when calling Whether the types match exactly. If the types do not match, we need to modify the code to ensure that the parameter type passed in matches the type of the parameter in the function definition.

2.2 Modify the number of parameters

If a compilation error "Cannot use invalid function arguments" occurs, we also need to confirm whether the number of parameters of the function is correct. If the number of parameters does not match, we need to add or remove parameters to ensure that the number of parameters passed in is the same as the number of parameters in the function definition.

2.3 Using function overloading

Another way to solve the compilation error "Cannot use invalid function argument" is to use function overloading. Function overloading refers to defining multiple functions with the same name but different parameter lists in the same scope. For example:

void print(int n) {
    std::cout << n << std::endl;
}

void print(double n) {
    std::cout << n << std::endl;
}

When the print function is called, the compiler will call the corresponding function according to the type of the parameter passed in. Function overloading can be used to easily handle situations where the number of parameters is different.

2.4 Using template functions

Another way to solve the compilation error "Cannot use invalid function argument" is to use template functions. A template function is a function that allows a function to adapt to multiple data types. For example:

template <typename T>
void print(T n) {
    std::cout << n << std::endl;
}

This template function can adapt to any data type. When calling this function, the compiler automatically infers the types of arguments.

The compilation error "Cannot use invalid function argument" is one of the problems often encountered in the C programming process. Understanding the root causes and solutions of compilation errors can help us locate and solve problems faster, and improve our programming efficiency.

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