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Sample C code using the Google C++ style guide
// Sample file using the Google C++ coding standard.
// General rules:
// - Indents are two spaces. No tabs should be used anywhere.
// - Each line must be at most 80 characters long.
// - Comments can be // or /* but // is most commonly used.
// - File names should be lower_case.c or lower-case.c
// Note: The Google C++ coding standard is a C++ coding standard. There are
// aspects specific to C that the coding standard does not specify, and these
// exceptions are noted below.
#include <stdlib.h>
#include <stdbool.h>
// For macros, use ALL_CAPS separated by underscore:
#define FLAG_FOO 0x0
// If a macro's replacement is not just a literal, enclose it in parentheses:
#define FLAG_BAZ (0x1 << 3)
// For constants, use k followed by PascalCase:
const int kStateFoo = 0;
// Type names should be PascalCase.
// Note: the Google coding standard does not specify how to format a struct
// name that has not been typedef-ed. I am following the lower_case separated
// by underscores format for now but this can be changed later.
typedef struct linked_list LinkedList;
// Enum values can either look like macros:
typedef enum {
} Mode;
// or they can look like contants:
typedef enum {
} State;
// Names of members of structs are lower_case and separated by underscores:
typedef struct sample {
int first_field;
bool second_field;
Mode mode;
State state;
struct sample *next;
} Sample;
// Function names are PascalCase. Opening braces come at the end of the last
// line for the function declaration rather than on the next line.
bool SampleEqual(Sample *self, Sample *other) {
// Local variables are lower_case and separated by underscores.
if (self == NULL && other == NULL) {
return true;
if (self == NULL || other == NULL) {
return false;
// For statements that span multiple lines, break after the logical operator
// and align each line with the start of the first line.
if (self->first_field == other->first_field &&
self->second_field == other->second_field &&
self->state == other->state &&
self->mode == other->mode &&
self->next == other->next) {
return true;
// If the previous block ends with areturn (or break or continue), do not
// follow it with an else.
return false;
// For function declarations that span multiple lines, then align subsequent
// lines with the first parameter.
Sample *SampleNew(int first_field,
bool second_field,
Mode mode,
State state,
Sample *next) {
Sample *sample = (Sample *) malloc(sizeof(*sample));
if (sample == NULL) {
return NULL;
memset(sample, 0, sizeof(sample));
sample->first_field = first_field;
sample->second_field = second_field;
sample->mode = mode;
sample->state = state;
sample->next = next;
return sample;
Sample *SampleClone(Sample *sample) {
if (sample == NULL) {
return NULL;
// For function calls that span multiple lines, align each subsequent line.
return SampleNew(sample->first_field,
// For function declarations (and function calls) where you cannot fit
// the parameters with the first after the opening parentheses, then align
// the parameters indented four spaces on the next line:
static void SampleDoSomethingWithALongName(
Sample *sample,
int parameter_with_a_long_name,
bool another_parameter,
int another_parameter) {
if (sample == NULL) {
// else and else if comes after the previous closing brace and not on the
// next line.
bool local_variable;
if (parameter_with_a_long_name == kStateFoo) {
local_variable = true;
} else {
local_variable = false;
sample->first_parameter += another_parameter;
sample->second_parameter |= local_variable;
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