语句

字符串

#include <stdio.h>
#include <string.h>

int main()
{
	//字符串是以\0结尾
	char arr1[] = "abc";
	char arr2[] = { 'a', 'b', 'c'};
	printf("%s\n", arr1);
	printf("%s\n", arr2);
	//字符串的长度
	printf("%d\n", strlen(arr1));//\0只是结尾标志
	printf("%d\n", strlen(arr2));//任意值
	system("pause");
	return 0;
}

选择语句

#define  _CRT_SECURE_NO_WARNINGS 1;
#include <stdio.h>
int main()
{
	int input = 0;
	scanf("%d", &input);
	if (input == 1)
	{
		printf("你选择了1");
	}
	else
	{
		printf("你选择了2");
	}
	system("pause");
	return 0;
}

循环语句

#define  _CRT_SECURE_NO_WARNINGS 1;
#include <stdio.h>
int main()
{
	int a = 0;
	while (a < 30)
	{
		printf("1a的值:%d\n",a);
		a++;
	}
	if (a = 30)
	{
		printf("2a的值:%d\n", a);
	}
	system("pause");
	return 0;
}

函数

//俩数相加
#define  _CRT_SECURE_NO_WARNINGS 1;
#include <stdio.h>

int add(int x, int y)
{
	int z = x + y;
	return z;
}
int main()
{
	int num1 = 0;
	int num2 = 0;
	scanf("%d %d", &num1, &num2);
	int sum = add(num1, num2);
	printf("sum=%d\n", sum);
	system("pause");
	return 0;
}

数组

数组：一组相同类型的元素的集合 (数组是用下标访问的)

#include <stdio.h>

int main()
{
	int arr[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
	char ch[5] = { 'a', 'b', 'c' };//不完全初始化，剩余的默认为0
	int i = 0;
	while (i <10)
	{
		printf("%d\n", arr[i]);
		i++;
	}
	system("pause");
	return 0;
}

[运算符]

参考了菜鸟教程(C 运算符 | 菜鸟教程 (runoob.com)) 算数运算符

a++和++a a--和--a的区别

#include <stdio.h>
int main()
{
	int c;
	int a = 10;
	c = a++;
	printf("先赋值后运算：\n");
	printf("Line 1 - c 的值是 %d\n", c);
	printf("Line 2 - a 的值是 %d\n", a);
	a = 10;
	c = a--;
	printf("Line 3 - c 的值是 %d\n", c);
	printf("Line 4 - a 的值是 %d\n", a);

	printf("先运算后赋值：\n");
	a = 10;
	c = ++a;
	printf("Line 5 - c 的值是 %d\n", c);
	printf("Line 6 - a 的值是 %d\n", a);
	a = 10;
	c = --a;
	printf("Line 7 - c 的值是 %d\n", c);
	printf("Line 8 - a 的值是 %d\n", a);
	system("pause");
	return 0;

}

关系运算符

#include <stdio.h>
int main()
{
	int a = 21;
	int b = 10;
	int c;

	if (a == b)
	{
		printf("Line 1 - a 等于 b\n");
	}
	else
	{
		printf("Line 1 - a 不等于 b\n");
	}
	if (a < b)
	{
		printf("Line 2 - a 小于 b\n");
	}
	else
	{
		printf("Line 2 - a 不小于 b\n");
	}
	if (a > b)
	{
		printf("Line 3 - a 大于 b\n");
	}
	else
	{
		printf("Line 3 - a 不大于 b\n");
	}
	/* 改变 a 和 b 的值 */
	a = 5;
	b = 20;
	if (a <= b)
	{
		printf("Line 4 - a 小于或等于 b\n");
	}
	if (b >= a)
	{
		printf("Line 5 - b 大于或等于 a\n");
	}
	system("pause");
	return 0;
}

位运算符

#include <stdio.h>
int main()
{

	unsigned int a = 60;    /* 60 = 0011 1100 */
	unsigned int b = 13;    /* 13 = 0000 1101 */
	int c = 0;

	c = a & b;       /* 12 = 0000 1100 */
	printf("Line 1 - c 的值是 %d\n", c);

	c = a | b;       /* 61 = 0011 1101 */
	printf("Line 2 - c 的值是 %d\n", c);

	c = a ^ b;       /* 49 = 0011 0001 */
	printf("Line 3 - c 的值是 %d\n", c);

	c = ~a;          /*-61 = 1100 0011 */
	printf("Line 4 - c 的值是 %d\n", c);

	c = a << 2;     /* 240 = 1111 0000 */
	printf("Line 5 - c 的值是 %d\n", c);

	c = a >> 2;     /* 15 = 0000 1111 */
	printf("Line 6 - c 的值是 %d\n", c);
	system("pause");
	return 0;
}

赋值运算符

#include <stdio.h>
int main()
{
	int a = 21;
	int c;

	c = a;
	printf("Line 1 - =  运算符实例，c 的值 = %d\n", c);

	c += a;
	printf("Line 2 - += 运算符实例，c 的值 = %d\n", c);

	c -= a;
	printf("Line 3 - -= 运算符实例，c 的值 = %d\n", c);

	c *= a;
	printf("Line 4 - *= 运算符实例，c 的值 = %d\n", c);

	c /= a;
	printf("Line 5 - /= 运算符实例，c 的值 = %d\n", c);

	c = 200;
	c %= a;
	printf("Line 6 - %%= 运算符实例，c 的值 = %d\n", c);

	c <<= 2;
	printf("Line 7 - <<= 运算符实例，c 的值 = %d\n", c);

	c >>= 2;
	printf("Line 8 - >>= 运算符实例，c 的值 = %d\n", c);

	c &= 2;
	printf("Line 9 - &= 运算符实例，c 的值 = %d\n", c);

	c ^= 2;
	printf("Line 10 - ^= 运算符实例，c 的值 = %d\n", c);

	c |= 2;
	printf("Line 11 - |= 运算符实例，c 的值 = %d\n", c);
	system("pause");
	return 0;

}