mirror of
https://github.com/jackyzha0/quartz.git
synced 2025-12-26 14:24:05 -06:00
131 lines
2.8 KiB
Markdown
131 lines
2.8 KiB
Markdown
---
|
|
title: "08-intro-to-c"
|
|
aliases:
|
|
tags:
|
|
- lecture
|
|
- cosc204
|
|
sr-due: 2022-09-29
|
|
sr-interval: 34
|
|
sr-ease: 250
|
|
---
|
|
|
|
Developed 1972 for Unix
|
|
|
|
- widely used
|
|
- compilers esxist for most OSs and architectiures
|
|
- diverse use
|
|
- OSs, device drivers, protocol stacks
|
|
- less so for application software
|
|
- low level
|
|
- language features map to CPU features
|
|
- not Object Oriented
|
|
- no classes etc
|
|
|
|
> “C is an imperative procedural language supporting structured programming, lexical variable scope, and recursion, with a static type system. It was designed to be compiled to provide low-level access to memory and language constructs that map efficiently to machine instructions, all with minimal runtime support. Despite its low-level capabilities, the language was designed to encourage cross-platform programming. A standards-compliant C program written with portability in mind can be compiled for a wide variety of computer platforms and operating systems with few changes to its source code.” - wikipedia
|
|
|
|
``` c
|
|
#include <stdio.h>
|
|
|
|
int main(int argc, const char *argv[])
|
|
{
|
|
puts("Hello World");
|
|
return 0;
|
|
}
|
|
```
|
|
|
|
# \#include
|
|
java uses .class files, C uses .c and .h
|
|
- .c for implementation
|
|
- .h for extern declarations (similar to `public`)
|
|
|
|
java uses `import`, C uses `#include`
|
|
|
|
``` c
|
|
#include <stdio.h>
|
|
#include "myfile.h"
|
|
```
|
|
|
|
- `#include` literally includes the file with the given name right there into the file eing compiled
|
|
- in `hello_world.c` we include `stdio.h` so we can call `puts()`
|
|
|
|
# Routines
|
|
``` c
|
|
int main(int argc, const char *argv[])
|
|
{
|
|
|
|
}
|
|
```
|
|
|
|
routines can be scoped to just the source code file
|
|
- `static int eleven(void`
|
|
|
|
routines must be declared bfore being used
|
|
- `extern int eleven(void):`
|
|
|
|
# if, const, for, while, do, case etc same as java
|
|
|
|
# Types
|
|
|
|
```
|
|
char
|
|
float, double
|
|
int, short, long
|
|
signed, unsigned
|
|
void
|
|
```
|
|
|
|
|
|
|
|
## sizeof
|
|
- to find out size of any type (built-in or user defined)
|
|
|
|
## stdint
|
|
|
|
|
|
## Structs
|
|
- like classes but without methods
|
|
- all fields public
|
|
- you can have structs in structs
|
|
|
|
## typedef
|
|
- any type can be given a new name using typedef
|
|
|
|
```
|
|
typedef struct
|
|
{
|
|
float x, y, z;
|
|
} coordinate;
|
|
```
|
|
|
|
## static
|
|
- the scope of this routine is local to this file
|
|
- this variable maintains its value between calls
|
|
|
|
```
|
|
void keeper(void) {
|
|
static uint64_t times_called = 0;
|
|
times_called++;
|
|
printf("Count:%llu\n", times_called);
|
|
}
|
|
```
|
|
|
|
## typecasting
|
|
like java
|
|
```
|
|
uint64_t y = 1024;
|
|
unit32_t x = (unit32_t) y;
|
|
```
|
|
|
|
## Keywords to ignore
|
|
- auto
|
|
- all local variables are auto
|
|
- register
|
|
- deprecated
|
|
|
|
## keywords to think about
|
|
- volatile
|
|
- do not optimize accesses to this variable
|
|
- might be changed by another thread or a harware event
|
|
- you're likely to see this in operating system souce code
|
|
- you're likely to see this in multithreaded programs
|