Writing error-free code is a crucial skill for any programmer. This guide will provide beginners with an overview of handling errors while writing C++ code. We will cover different types of errors, including configuration errors, compile errors, link errors, and bugs. Each section will be accompanied by game-like examples to illustrate the concepts effectively.
Configuration Errors
Configuration errors occur when the development environment is not set up properly. These errors can prevent your code from compiling or running correctly. Here are some common configuration errors you may encounter:
For example, let’s say you’re developing a game and you receive a configuration error stating that the required graphics library is not found. This error indicates that the necessary configuration for your graphics library is missing. To resolve this, you need to ensure that the library is properly installed and its paths are correctly set in the project settings. An example article that covers this skill is Setting up the Visual Studio development environment.
Compile Errors
Compile errors occur when there are mistakes or inconsistencies in your code that prevent the compiler from translating them into machine-readable instructions. These errors are often caused by syntax errors, type mismatches, or missing declarations.
As an example, suppose you’re creating a game character class, and you forget to include a semicolon at the end of a class definition. This will result in a compile error, and the compiler will highlight the missing semicolon. To fix this error, simply add the semicolon at the appropriate location. These are the most common type of error and fortunately, the easiest to fix.
Here’s an example of a compile error in C++ code. Can you work it out for yourself?
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#include <iostream> int main() { int x = 10; int y = "20"; // Error: Type mismatch int sum = x + y; std::cout << "The sum is: " << sum << std::endl; return 0; } |
In the preceding example, we have a simple program that adds two numbers and prints the result. However, there is a compile error in the code. Let’s analyze the error:
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int y = "20"; // Error: Type mismatch |
The error occurs because we are trying to assign a string value (enclosed in double quotes) to an integer variable y. This is a type mismatch because y is declared as an integer, but we are assigning a string value to it.
When you try to compile this code in Visual Studio, you will receive an error message indicating the type mismatch:
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error: invalid conversion from 'const char*' to 'int' |
To fix this compile error, you need to ensure that the variable y is assigned an integer value instead of a string. For example:
By correcting the type mismatch, the code will compile successfully, and you will get the desired output without any errors.
Link Errors
Link errors occur during the linking phase of compilation when the compiler tries to combine different object files and libraries to create the final executable. These errors are typically caused by missing function definitions or unresolved external symbols.
An example might help. Imagine you’re working on a game that uses a physics library. If you forget to include the necessary physics library files or provide the required function definitions, you will encounter a link error. To resolve this, ensure that you have included all the required libraries and properly link them with your project. To properly link all the files in an SFML game project, read this article: Building your first SFML game project.
Here’s another beginner-friendly example of a link error in C++ code:
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#include <iostream> int main() { sayHello(); // Error: Undefined reference to 'sayHello' return 0; } void sayHello() { std::cout << "Hello, World!" << std::endl; } |
In this example, we have a program that attempts to call a function called sayHello() within the main() function. However, there is a link error in the code. Let’s analyze the error:
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sayHello(); // Error: Undefined reference to 'sayHello' |
The error occurs because the compiler can’t find the definition of the sayHello() function during the linking phase. In this case, the function declaration is below the main() function, so the compiler doesn’t have the necessary information to link the function call properly.
When you try to compile this code in Visual Studio, you will receive a link error message similar to:
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error LNK2019: unresolved external symbol "void __cdecl sayHello(void)" (?sayHello@@YAXXZ) referenced in function _main |
To fix this link error, you need to ensure that the function definition ( void sayHello()) is placed above the main() function:
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void sayHello() { std::cout << "Hello, World!" << std::endl; } int main() { sayHello(); // Function call return 0; } |
By placing the function definition above the main() function, the linker can find the definition of sayHello() and successfully link the function call. This resolves the link error, and the program will execute as expected, printing “Hello, World!” to the console.
Bugs
Bugs are issues that arise during the execution of your program. They can cause unexpected behavior, crashes, or incorrect results. Debugging is the process of identifying and fixing bugs.
Suppose you’re creating a game where the player’s character keeps falling through the floor. This unexpected behavior is a bug. To identify the cause, you can use the Visual Studio debugger. Set breakpoints, step through the code, and inspect variables to find the error. In this case, you might discover that the collision detection code is incorrect, and fixing it will resolve the bug.
Here’s an example of a bug in C++ code:
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#include <iostream> int main() { int x = 5; int y = 0; int division_result = x / y; std::cout << "The division result is: " << division_result << std::endl; return 0; } |
In this example, we have a program that calculates the division of two numbers and prints the result. However, there is a bug in the code. Let’s analyze the bug:
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int division_result = x / y; |
The bug occurs because we are dividing the variable x by y, but y is assigned the value of . Of course, y could be equal to zero because of the way the player played the game, and therefore impossible for the compiler to know before the game is played. Hence this is a bug, not a compile or link error. This will result in a division by zero error, which is undefined behavior in C++.
When you run this code in Visual Studio, you will encounter a runtime error:
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Unhandled exception at 0x004115D2 in Example.exe: 0xC0000094: Integer division by zero. |
To fix this bug, you need to ensure that the divisor ( y) is not equal to zero before performing the division. For example, you can add a check to prevent division by zero:
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int division_result; if (y != 0) { division_result = x / y; } else { std::cout << "Error: Division by zero is not allowed." << std::endl; // Handle the error or exit the program gracefully } |
By checking if the divisor is zero before performing the division, you can prevent the bug and handle the error appropriately.
Summary
Handling errors while writing C++ code is an essential skill for developers. By understanding and addressing configuration errors, compile errors, link errors, and bugs, you can write more robust and reliable programs. Remember to pay attention to error messages, use the debugging tools available in the Visual Studio environment, and continually improve your coding skills to minimize errors and create high-quality games.
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