What is the difference between assembly language and c language?

Difference: 1. Because assembly language is essentially a mnemonic for machine language and is a language that directly faces the CPU, the operating efficiency of assembly language is higher than that of C language; 2. The reliability of assembly language on hardware It has strong controllability, but the controllability of C language hardware is relatively poor; 3. The object code of assembly language is small, and the object code of C language is large; 4. Assembly language is not easy to maintain, but C language is easy to maintain; 5. Assembly language is very portable. Poor, C language is very portable; 6. Assembly language is easier to learn than C language, because assembly language requires a lot of programming knowledge and is very complex.

The operating environment of this tutorial: windows7 system, c99 version, Dell G3 computer.

What is c language:

C language is a general computer programming language and is widely used. The design goal of the C language is to provide a programming language that can be easily compiled, handle low-level memory, generate a small amount of machine code, and can run without any runtime environment support; although the C language provides many low-level processing functions, However, it still maintains good cross-platform characteristics. C language programs written in a standard specification can be compiled on many computer platforms, including some embedded processors (single chip microcomputer or MCU) and supercomputers and other operating platforms.

What is assembly language:

Assembly language (assembly language) is a language used in electronic computers, microprocessors, and microcontrollers or other low-level languages ​​for programmable devices, also known as symbolic languages. In assembly language, mnemonics are used to replace the opcodes of machine instructions, and address symbols (Symbol) or labels are used to replace the addresses of instructions or operands. In different devices, assembly language corresponds to different machine language instruction sets, which are converted into machine instructions through the assembly process. Generally speaking, a specific assembly language and a specific machine language instruction set have a one-to-one correspondence and cannot be directly transplanted between different platforms.

Many assemblers provide additional support mechanisms for program development, assembly control, and auxiliary debugging. Some assembly language programming tools often provide macros, which are also called macro assemblers.

Assembly language is not as widely used in programming as most other programming languages. In today's practical applications, it is usually used in low-level, hardware operations and demanding program optimization situations. Assembly language is required for drivers, embedded operating systems, and real-time running programs.

The difference between assembly language and c language

1. Different efficiency

Assembly language efficiency High, C language efficiency is relatively low.

2. Different controllability of hardware

Assembly language has strong controllability of hardware, while C language has poor controllability of hardware.

3. Different code sizes

The assembly language target code has a small size, while the C language target code has a large size.

4. Different maintainability

Assembly language is not easy to maintain, but C language is easy to maintain.

5. Different portability

Assembly language has poor portability, while C language has very good portability.

6. Different learning difficulties

Assembly language requires a lot of complex programming knowledge and is often used by developers. C language is a very simple and convenient language, and programmers do not need to have much professional knowledge.

Expand knowledge: The reason why assembly language runs efficiently

1. Assembly language is essentially a mnemonic for machine language .

CPU can only run the instruction set it supports, and each instruction in these instruction sets is a sequence of binary numbers, that is, an ordered combination of "0" and "1" ; The combination of "0" and "1" is not convenient for programmers to remember, so there are mnemonics such as "MOV A 0x40".

So compiling assembly language into machine language executable by the CPU only requires a translation action. After writing a program in C language, a compiler needs to be used to compile the C language into machine language corresponding to the corresponding CPU instruction set.

Assembly language and machine language have a one-to-one correspondence. But what about C language? Of course it's not such a good thing.

The syntax of C language is fixed. When a program written in C language is compiled into machine language instructions that the CPU can understand, there is no one-to-one correspondence. Therefore, compilation rules are required, so the operating efficiency is lower. It can also be said that C language is a language for programmers, while assembly language is a language directly for the CPU.

2. Assembly is a language that directly faces the CPU. As long as it is within the scope supported by the instruction set, assembly language can directly and flexibly manage special function registers, general-purpose registers, and storage. Every byte of the unit, even every bit.

The C language is also very powerful in its use and management of memory, but after all, it is still subject to syntax. To give the simplest example, there is no variable type corresponding to three bytes or five bytes in C language, either int type or long type, so each application must be a fixed number of bytes, which will inevitably cause memory usage. waste.

Most assembly languages ​​do not have such syntax at all. With the help of pseudo-instructions (which actually only improve readability), assembly language programs can use variables of any number of bytes. Of course, the processing is faster than C language is much more troublesome. In the end, it is still processed byte by byte, but writing a program in C language is easier. Don't worry about it, the compiler will eventually take care of it.

The price of ease is waste. Inefficient memory usage will also affect the overall efficiency of the entire program.

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