Difference Between Compiler and Interpreter: Compiler Vs Interpreter

If we were to go to a foreign country, where communicating in the native language is difficult, life would have been hazardous. Expecting something in return when asked would be tough unless we have a translator. Even though we don’t go to a different nation every day, we communicate with someone who does not understand any human language; A computer. We speak to a computer through a high-level programming language but did you know that the programming language isn’t the ultimate language that a computer understands? We have system software known as compilers and interpreters that aids in making the conveyance smoother. What are these compilers and interpreters? Are they the same? Is there any difference between compilers and interpreters?

Both compiler and interpreter are key components needed to convert a program written in a high-level language into machine code that can be understood by a computer. A compiler and an interpreter, however, function very differently, and there are some differences between the two. In this article, we are going to see what are compilers and interpreters as well as the difference between Compiler and Interpreter.

What is a Compiler?

A compiler is computer software that readily translates programming language into machine code or assembly language or low-level language. It translates every program to binary(1’s and 0’s) that a computer feasibly understands and does the task that corresponds to the code. One condition that a compiler has to follow is the syntax of the programming language that is used. Thus, if the syntax of the program does not match the analysis of the compiler, an error arises that has to be corrected manually in the program written. 

How Compilers Work?

The main work of the compiler is to translate the program into machine code and let the programmer know if there are any errors, ranges, limits, etc., especially syntactical errors in the program. It analyses the entire program and converts it into machine code. The working of a compiler can be categorized into the following phases:

• Lexical analysis: Splitting of source code into an abstract fragment known as lexeme. A token is generated for each of the lexemes, referring to whether it is a keyword, a string, or some other variable. 

• Syntax Analysis: The tokens assigned are structured to form an Abstract Syntax Tree(AST) and checked for errors in the syntax. 

• Semantic Analysis: The AST is checked for semantic errors like the wrong variable assigned, using an undeclared variable, using keywords as variable, etc.

• Intermediate Code Generation: The process of compilation generates two or more intermediate code forms.

• Optimization: The compilation process looks for multiple ways through which the task can be enhanced. 

• Code generation: The compiler converts the intermediate optimized code into a machine code after which the source program is converted to an object program.

Benefits of using a Compiler

The compiler offers various advantages which can be summed up as follows:

• Compilers translate programs in a single operation.
• The process takes less time.
• CPU utilization is higher.
• The checking of syntactic and semantic errors can be done simultaneously.
• Many high-level languages, including C, C++, and Java, support it easily.

Role of a Compiler

• It reads the source code and provides an executable code.
• Translates programs written in a high-level language to a language that the CPU can understand. 
• The process is relatively complicated and takes time for analysis.
• The executable code will be in machine-specific binary code. 
• Total run time is more and occupies a large part of the memory. 

What is an Interpreter?

An interpreter is a computer program that converts program statements into machine code. Program statements include source code, pre-compiled code, and scripts. Unlike a compiler, an interpreter takes a shorter amount of time to interpret a program. Since interpreters simplify the process of working with source code, they are especially useful for beginners.

How Does an Interpreter Work?

An interpreter works more or less similar to a compiler. The only difference between their working is that the interpreter does not generate any intermediate code forms, reads the program line to line checking for errors, and runs the program simultaneously. 

Benefits of using Interpreters

The interpreter offers various advantages which can be summed up as follows:

• It is responsible for translating the program line by line.
• Interpreters are smaller in size.
• Flexibility is its strength.
• The process of error localization is simplified.
• Interpreters are used to simplify the implementation of computer programming language constructs and make it easier for programs to run.

Role of an Interpreter

• It converts program statements, line by line, into machine code.
• Allows modification of the program while executing. 
• Relatively lesser time is consumed for analysis as it runs line by line. 
• Execution of the program is relatively slow as analysis takes place every time the program is run.

Difference Between Compiler and Interpreter

While it looks like Compiler and Interpreter work the same by translating programs into machine code, there is a very thin line that differentiates of them. The differences are as follows:

Basis	Compiler	Interpreter
Analysis	The entire program is analyzed in a compiler in one go.	In an interpreter, a line-by-line analysis is performed on the program.
Machine Code	Stores machine code in the disk storage.	Machine code is not stored anywhere.
Execution	The execution of the program happens only after the entire program is compiled.	The execution of the program takes place after every line is evaluated and hence the error is raised line by line if any.
Run Time	Compiled program runs faster. Since it consumes less time, it is much faster than an interpreter.	Interpreted program runs slower. Since it consumes more time, it is much slower than an compiler.
Generation	The compilation gives an output program that runs independently from the source file.	The interpretation does not give any output program and is thus evaluated on every execution.
Optimization	The compiler reads the entire program and searches multiple times for a time-saving execution.	No rigorous optimization takes place as code is evaluated line by line.
Error and error execution	All the errors are shown at the end of the compilation and the program cannot be run until the error is resolved.	Displays the errors from line to line. The program runs till the error is found and proceeds further on resolving.
Input	The compiler takes in the entire program for analysis.	The interpreter takes in lines of code for analysis.
Output	The compiler gives intermediate code forms or object code.	The interpreter does not generate any intermediate code forms.
Programming languages	C, C++, C#, Java are compiler-based programming languages.	PHP, PERL, Ruby are interpreter-based programming languages.
CPU Utilization	CPU utilization is higher in compilers.	The interpreter uses less CPU than the compiler.
Error Localization	Localizing errors is difficult.	Errors can be localized more easily than in the compiler.
Error Effects	An error can trigger the reorganization of the entire program.	Errors only cause part of the program to be reorganized.
Flexibility	In general, compilers are not flexible.	The interpreter provides more flexibility.
Error Verification	You can simultaneously check for both syntactic and semantic errors.	Syntactic errors are checked only.

Conclusion

To sum up, the compilers and the interpreters are like an oven and induction stove. Its functioning is almost the same; To convert a programming language into a machine language. But, the working differs. Their usage depends on the language being used and the purpose. 

Frequently Asked Questions

Q.1: Which is better: A compiler or an Interpreter?

Ans: The betterness depends on the need. The interpreter is highly useful in debugging but the overall execution is slow. While a compiler scans the entire source code, resolving errors is slightly difficult. Selection is purely dependent on the end result. 

Q.2: Which is faster? Compiler or Interpreter? 

Ans: If the process is considered, the Interpreter is faster than the compiler. However, once a program is compiled, Runtime or execution is faster for a compiled program over-interpreted ones. 

Q.3: Can anyone use an interpreter instead of a compiler? 

Ans: Yes. Interpreters have advantages like easier debugging, portability, etc. Depending upon the necessity, one can use an interpreter instead of a compiler. 

Q.4: Is Python an interpreter or a compiler? 

Ans: Python is known to be an interpreted language. However, the compilation of Python code is hidden from users. The Python programs get converted to bytecodes, an intermediate form that the machine understands. Thus, Python stands in the centre of both parameters. 

Q.5: What are the examples of interpreters? 

Ans: Some examples of interpreters include Python interpreters, PERL interpreters, Ruby interpreters, PHP interpreters, etc.

Additional Resources

• Compiler Design MCQ
• Online Java Compiler
• Online C++ Compiler
• Online C Compiler
• Online Python Compiler
• Online Javascript Compiler