What's the relationship between an assembler and a linker?

An assembler translates assembly language into machine code, while a linker combines multiple object files into a single executable program.

An assembler and a linker are both crucial components in the process of converting high-level programming languages into executable programs. They each perform distinct roles in this process. The assembler's job is to translate assembly language, which is a low-level programming language, into machine code. Machine code is the lowest level of programming language, consisting of binary instructions that can be directly executed by the computer's hardware.

The assembler does this translation in a two-step process. First, it scans the entire assembly program and maps all the labels to their corresponding memory locations. This is known as the 'first pass'. During the 'second pass', the assembler translates the assembly language instructions into machine code. It also replaces all symbolic references with their corresponding memory locations, determined during the first pass.

On the other hand, a linker is a program that takes one or more object files generated by a compiler and combines them into a single executable program. Object files are intermediate files that contain machine code but are not yet executable. They are produced by the compiler after it translates the high-level source code into machine code.

The linker's job is to resolve all symbolic references between object files. For example, if a function in one object file refers to a function in another object file, the linker will find the memory location of the second function and replace the symbolic reference with this memory location. The linker also combines all the object files into a single executable file, which can be run on the computer.

In summary, the assembler and the linker both play essential roles in the process of turning high-level programming languages into executable programs. The assembler translates assembly language into machine code, while the linker combines multiple object files, resolves symbolic references, and produces a single executable program.