C++ compilation error: Invalid type conversion, how to deal with it?

C, as a strongly typed language, requires special attention when converting data types, otherwise the compiler will report an error. One of the more common errors is "invalid type conversion". This article will explain why this error occurs, how to perform type conversion, and how to avoid this error.

1. Cause of error

1. Data type mismatch

There are some data types in C that cannot be converted directly. For example, you cannot convert a character variable directly to an integer variable, or a floating-point variable directly to a Boolean variable. If you force a type conversion, an "invalid type conversion" compilation error will occur.

2. Implicit type conversion error

The C compiler will automatically perform some type conversions, but sometimes these automatic conversions are not what we expect. For example, if you assign a double variable to an int variable, the compiler will automatically round off the decimal point. However, if the value of the double variable exceeds the value range of the int, an "invalid type conversion" will occur. mistake.

3. Assignment statement error

In C, type conversion will occur in the assignment statement, such as assigning a string constant to a character array variable. But if the lengths of the two data types do not match, or the format of the string constant is incorrect, an "invalid type conversion" error will occur.

2. Type conversion method

1. C forced type conversion

In C, we can use the forced type conversion operator to perform type conversion. Casting can convert one data type to another data type, but it should be noted that casting may change the value of the data type, the range or precision of the data type, etc.

Forced type conversion operators include: static_cast, dynamic_cast, const_cast, reinterpret_cast.

2. Appropriate use of library functions to achieve type conversion

Library functions have relatively mature and credible algorithms for implementing type conversion, so when using type conversion you should Prioritize using library functions for implementation rather than hand-written code for conversion.

For example, use the atof() function to convert a string into floating-point data, and use the atoi() function to convert a string into integer data.

3. Custom data type conversion function

Sometimes, C’s built-in data type conversion method cannot meet the requirements, or complex business logic processing is required to complete the type Convert. In this case, we can customize the data type conversion function to achieve this.

3. How to avoid "invalid type conversion" error?

1. Strictly abide by the rules of data type conversion

When performing type conversion, you must strictly abide by the language specifications and do not mix different types of data or force the data Convert to unsuitable data type. Type conversions should only be performed if there are clear rules and needs.

2. Perform type checking when using forced type conversion

When using forced type conversion, you must first perform type checking to ensure the legality of the type. For custom type conversion functions, type checking must also be performed inside the function to avoid type conversion errors outside the function.

3. Use a high-level compiler

Modern compilers do a good job of checking type conversions. Using a high-level compiler can automatically detect potential type conversion errors in the code and give specific error prompts.

Summary:

In C, the "invalid type conversion" error is one of the compilation errors that developers often encounter. In order to avoid this kind of error, developers should strictly abide by the rules of data type conversion, perform type checking when using forced type conversion, and give priority to using library functions for type conversion. At the same time, using a high-level compiler can also effectively detect potential type conversion errors in the code.

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