C Coding Standard Recommendations

This is a preliminary attempt to come up with a set of C coding recommendations for Upgrade Silicon Software developers. A meeting was held on 20 April 1995 to come up with a set of standards. This is just a compilation of all the recommendations. It should be noted that not all of the recommendations are meant to be strictly followed. (Any statement with MUST is to be strictly followed. Anything with SHOULD is strongly recommended)

Header Files

Every Header file must include:


     #ifndef <FILENAME_H>
     #define <FILENAME_H>
     .
     .
     .
     #endif

at the start with a name which corresponds to filename.h. For example, if you have a file called types.h, the first two lines in that file ignoring comments must be:


     #ifndef TYPES_H
     #define TYPES_H
     .
     .
     .
     #endif

Declarations

The "pointer" qualifier, '*', must be with the variable name rather than with the type.

char *s, *t, *u;

instead of

char* s, t, u;

as C compilers may handle these assignments differently.

Functions

Prototyping - Functions must be prototyped in a Header file. Prototyping a function means to declare the function and all its arguments types and return type in a Header file so that it can be made global to all code.
Naming Conventions - Function names should look as follows: lllOoo...Aaa...(), where lll indicates the library that the function is associated with, Ooo... is the object the function acts on, and Aaa... is the action performed on the object.
For example, in VxWorks you can probe the ASI memory address space for bus errors using the routine vxMemProbe(). In this example, vx is the library the function is associated with, Mem is the object acted on by the function and Probe is the action performed on the object Mem.
Internal functions in a module must be declared static.
Input variables to functions which are not altered should be passed with const type qualifier.

Code Formatting

ALL code must be written in ANSI standard format.
Names with leading and trailing underscores MUST NOT be used as they are reserved for system purposes.
#define constants must be in all CAPS.
Should only write one statement per line.
Not Okay:
int x; int y; int z; for(x=0;x<200;x++){y=x; z=y*x; printf("%d\n",z);}
Okay:
int x, y, z;
for(x = 0; x < 200; x++) {
y=x;
z=y*x;
printf("%d\n",z);
}
Code should be indented, so that it is easier to read
For Example:
```
if (x=1) {
  x=2;
}
```
or
```
if (x=1)
  {
  x=2;
  }
```

Macros

Refrain from using macros except when absolutely necessary. If used, the name of the macro must clearly describe what it does. This will save a great deal of time in searching through code to find what the macro does.

Send any comments or suggestions to

lpaterno@d0sf26.fnal.gov

Last Updated : 19-March-1996