C 语言基础知识笔记

基础数据类型

#include <stdio.h>
#include <limits.h>

int main()
{
    short s = 1;
    int i = 1000;
    long l = 1000000;
    char c = 'A';
    float f = 1.0;
    double d = 1.0;

    int max_int = INT_MAX;
    printf("max_int = %d \n", max_int);
    printf("max_int + 1 = %d \n", max_int + 1);

    long max_long = LONG_MAX;
    printf("max_long = %ld \n", max_long);
    printf("long byte length = %lu \n", sizeof(long));

    long long max_longlong = LLONG_MAX;
    printf("max_long = %lld \n", max_longlong);
    printf("long long byte length = %lu \n", sizeof(long long));

    return 0;
}

三大执行结构

2. else-if

if (表达式1)
    语句1
else if (表达式2)
    语句2
else if (表达式3)
    语句3
else if (表达式4)
    语句4
else
    语句5
 

3. switch

switch (表达式) {
    case 常量表达式: 语句序列
    case 常量表达式: 语句序列
    default: 语句序列
}

C 数组

字符串

函数

结构体

C程序基础笔记之结构体

内存管理之 malloc

C 枚举

#include <stdio.h>

enum week
{
    Mon,
    Tues,
    Wed,
    Thurs,
    Fri,
    Sat,
    Sun
};
// Mon、Tues、Wed 等都是常量

int main()
{
    enum week a, b, c;
    a = Mon;
    enum week d = Sat;

    if (a == Mon)
    {
        printf("hello world!\n");
    }
    if (d == 5)
    {
        printf("hello world!\n");
    }
    printf("%d\n", d);
    return 0;
}

C 指针