C++ compilation error: wrong function parameters, how to fix it?

C is a popular programming language that is widely used in software development and systems programming. When the C compiler parses source code, it checks the syntax and semantics of the code and generates an executable file or library. When the compiler encounters a problem, it will output a certain error message to tell the programmer the specific location and cause of the error. This article will discuss a common C compilation error - wrong function parameters, and explore how to fix it.

1. Error message example

The following is a simple C program, an example of an error that will occur when compiling:

#include <iostream>
using namespace std;

int sum(int a, int b) {
    return a + b;
}

int main() {
    int c = sum(1, "2");
    cout << "c= " << c << endl;
    return 0;
}

When compiling the above program, an error message will be prompted :

main.cpp: In function ‘int main()’:
main.cpp:8:22: error: invalid conversion from ‘const char*’ to ‘int’ [-fpermissive]
    int c = sum(1, "2");
                      ^

This error message tells us that the sum function is called in the main function and two parameters 1 and "2" are passed. However, the second parameter type is const char*, not int. The compiler was unable to convert a string constant to an integer type, thus reporting the above compilation error.

2. How to solve the error?

Wrong function parameters are one of the common errors in C programs, but they are usually easy to fix. Here are some solutions:

1. Changing parameter types in function calls

In the above example, we can change the type of the second parameter to int, thus Resolve errors. The modified program code is as follows:

#include <iostream>
using namespace std;

int sum(int a, int b) {
    return a + b;
}

int main() {
    int c = sum(1, 2);
    cout << "c= " << c << endl;
    return 0;
}

In this code, we modify the second parameter to an integer type, thus avoiding compilation errors and the program can compile and run normally.

2. Change the parameter type in the function definition

Another workaround is to change the parameter type in the function definition. In the above example, we have defined a sum function that expects two parameters, both of type int. If the caller passes incorrect parameter types, the compiler reports information about the error. If we want to pass parameters of different types, we need to change the parameter types in the function definition.

For example, let's say we want to pass a float as the second parameter in the above example. Then you can modify the function definition to:

#include <iostream>
using namespace std;

int sum(int a, float b) {
    return a + b;
}

int main() {
    int c = sum(1, 2.5f);
    cout << "c= " << c << endl;
    return 0;
}

In the above code, we change the type of the second parameter of the sum function to float. In the main function, we passed a floating point number 2.5f as the second parameter. Since the parameter types in the function definition match the actually transferred parameter types, the compiler no longer reports information about the error.

3. Summary

Wrong function parameters may be one of the most common errors in C programming. It is usually caused by incorrect or mismatching types of function parameters. To resolve this type of error, you can check the compiler's error message and try to change the parameter type in the function call or the parameter type in the function definition to the correct type. By understanding the causes and solutions to C compilation errors, we can write higher quality C programs.

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