Quick Reference

printf

printf(STRING, VARIABLES)

Prints the string.

int foo = 0;
int bar = 10;

printf("The value of foo is %d, the value of bar is %d\n", foo, bar);

scanf

scanf(VAR TYPE, ADDRESS OF VARIABLE)

Awaits user input and puts it into a specific address.

int user_input;

scanf("%d", &user_input);

if else ...

if(condition) {
  EXECUTE CODE
} else if(condition) {
  EXECUTE CODE
} else {
  EXECUTE CODE
}

If a condition is true (condition != 0), then execute the code. If the condition is not true, then move to the next else or if statement.

int foo = 20;
int bar = 10;

if((foo - bar) > 10) {
  printf("first condition");
} else {
  printf("second condition");
}

Because foo - bar is equal to 10. The first condition is not true. Thus we print second condition.

variable types

char       Typically a single octet(one byte). This is an integer type.
int          The most natural size of integer for the machine.
float       A single-precision floating point value.
double   A double-precision floating point value.
void        Represents the absence of type.

pointers

VARTYPE *VARNAME;

Pointers are a special type of variable in c that hold a value of a memory address. It is possible to deference pointers using the dereference operator *. This returns the value of the memory address pointed to by the pointer. It is also possible to obtain the address of the pointer itself using the reference operator &.

int n;
int *p;

n = 10;
p = &n;

printf("The value of n is %d", n);
printf("The value of n is %d", * p);

printf("The address of n is %p", &n);
printf("The address of n is %p", p);

printf("The address of p is %p", &p);

Arrays