The difference between java and c

Java and C are both imperative languages ​​(Imperative Language). The difference is that Java has object-oriented (OO) components in it, while C is completely process-oriented. The advanced versions of C, C and C#, support OO components. object.

Another difference is that Java is cross-platform, and different operating systems can interpret Java programs through the JVM, while C, C, and C# It is platform-related, and some instructions can only be executed in certain operating systems. (Recommended learning: java course)

The specific reason is that Java is an interpreted language, and all codes will be translated into unified, system-independent bytecode and then placed in the JVM Run on the computer; while C is a compiled language, the code must first be converted into system-related intermediate code by the compiler before it can be run.

Another difference is that Java does not support system calls and cannot interact with the operating system. This is determined by its cross-platform characteristics, while C can call instructions in the system, such as fork() . This is why there is only the concept of thread (Thread) in Java but not the concept of process (Process), while C has both.

Furthermore, Java cannot control memory, while C can artificially allocate memory through pointers.

Another point is that Java has a Gabbage Collection mechanism that can automatically reclaim space that is no longer used, while C uses the free() function to release space.

In terms of speed, programs written in C language are better than Java, because Java must run in a virtual machine environment, but because of the virtual machine, Java gains platform independence, while C language The program may need to be re-modified and compiled to achieve platform porting.

On the other hand, the C language is more "low-level" than the Java language, so hardware drivers, for example, can be written in C, but Java cannot. Another obvious difference between Java and C language is that C language focuses on algorithms, but Java is different. You can just import the package when you want to use it.

Algorithms in C language are very important, but algorithms in Java are not as complex as C language. Printing method: C language is printf("……."); Java is System.out.print("……."), you can also use println, ln means line break.

The basic data types in Java programs (boolean, char, byte, short, int, long, float, double) are references to objects; C language also has many basic types, as well as struct, union ,enum, arrays and pointers.

There are no enumeration or union types in Java. Java uses the Unicode character set, and C language usually uses the ASCII character set, A-65, a-97. Variables in C language do not need to be initialized, but variables in Java must be initialized.

In C language, the char type occupies one byte, and in Java, the char type occupies 2 bytes.

In general, Java is easier to get started and faster to learn than C, but it is not as helpful as C for understanding programming languages.

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