C语言代码练习（test_1_20）

#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>

int main()
{
	int a = 5;
	//a++;//后置++
	++a;

	printf("%d\n", a);//

	return 0;
}

前置++
int main()
{
	int a = 5;
	int b = ++a;//先+1，后使用
  //a=a+1, b=a
	printf("a=%d b=%d\n", a, b);

	return 0;
}

后置++
int main()
{
	int a = 5;
	int b = a++;//先使用，再+1
	//b=a, a=a+1
	printf("a=%d b=%d\n", a, b);//a=6 b=5

	return 0;
}


int main()
{
	int a = 5;
	int b = --a;//先-1，再使用
	//a=a-1, b=a
	printf("a=%d b=%d\n", a, b);//

	return 0;
}

int main()
{
	int a = 5;
	int b = a--;//先使用，后-1
	//b=a, a=a-1
	printf("a=%d b=%d\n", a, b);//

	return 0;
}


int main()
{
	int a = 5;
	printf("%d\n", a--);//

	return 0;
}

int main()
{
	int a = 10;
	printf("%d\n", a);
	printf("%d\n", +a);

	return 0;
}



int main()
{
	int a = 10;
	printf("%d\n", a);
	printf("%d\n", -a);

	return 0;
}

直接写出的字面浮点数，会被编译器直接识别为double
int main()
{
	3.14;//double
	3.24f;//float

	int a = (int)3.14;
	printf("%d\n", a);
	return 0;
}

standard
input
output

int main()
{
	printf("hehe\n");
	printf("haha\n");
	return 0;
}


int main()
{
	printf("hello \nworld\n");

	printf("hello ");
	printf("\n");
	printf("world");

	return 0;
}




int main()
{
	printf("hehe");
	return 0;
}

#include <stdio.h>



int main()
{
	printf("there are 5 apples\n");

	int n = 0;
	//给n输入一个值

	printf("there are %d apples\n", n);

	return 0;
}

int main()
{
	printf("zhangsan will come tonight\n");

	printf("%s will come tonight\n", "zhangsan");
	printf("%s will come tonight\n", "lisi");
	printf("%s will come tonight\n", "wangwu");
	printf("%s will come tonight\n", "cuihua");


	return 0;
}

int main()
{
	printf("%s says it is %d o'clock\n", "wangwu", 20);

	return 0;
}


int main()
{
	int a = -10;
	printf("%d\n", a);
	printf("%u\n", a);

	return 0;
}

int main()
{
	int a = 0;
	scanf("%f", &a);
	printf("%d\n", a);
	return 0;
}

int main()
{
	printf("%d\n", 123);
	printf("%5d\n", 123);
	printf("%-5d\n", 123);
	printf("%5d\n", 1234567);

	return 0;
}



#include <stdio.h>
int main()
{
    printf("%f\n", 123.45);
    printf("%12f\n", 123.45);

    return 0;
}


#include <stdio.h>
int main()
{
    printf("%+d\n", 12);
    printf("%+d\n", -12);

    return 0;
}


int main()
{
	printf("%f\n", 123.45);
	printf("%.2f\n", 123.45);
	printf("%.1f\n", 123.45);

	printf("%f\n", 0.5);
	printf("%.2f\n", 0.5);
	printf("%6.2f\n", 123456.5);

	printf("%*.*f\n", 6, 2, 0.5);

	return 0;
}


//https://legacy.cplusplus.com/reference/cstdio/printf/?kw=printf
//https://zh.cppreference.com/w/c/io/fprintf


int main()
{
	printf("hello world\n");
	printf("%s", "hello world\n");
	printf("%.3s", "hello world\n");


	return 0;
}




int main()
{
	int score = 0;
	//输入一个成绩

	printf("请输入成绩:");
	scanf("%d", &score);//& - 取地址符号
	printf("成绩是: %d\n", score);

	return 0;
}



int main()
{
	int i = 0;
	int j = 0;
	float x = 0.0f;
	float y = 0.0f;

	scanf("%d%d%f%f", &i, &j, &x, &y);

	printf("i=%d\n", i);
	printf("j=%d\n", j);
	printf("x=%f\n", x);
	printf("y=%f\n", y);

	return 0;
}



#include <stdio.h>

int main()
{
    int x;
    float y;

    // 用户输入 "    -13.45e12# 0"
    scanf("%d", &x);
    printf("%d\n", x);
    scanf("%f", &y);
    printf("%f\n", y);
    return 0;
}

#include <stdio.h>

int main()
{
    int x;
    float y;

    // 用户输入 "    -13.45e12# 0"
    scanf("%d%f", &x, &y);
    printf("x=%d\n", x);
    printf("y=%f\n", y);
    return 0;
}




int main()
{
	int a = 0;
	int b = 0;
	float f = 0.0f;
	int ret = scanf("%d %d %f", &a, &b, &f);

	printf("ret = %d\n", ret);

	printf("a = %d\n", a);
	printf("b = %d\n", b);
	printf("f = %f\n", f);

	return 0;
}




int main()
{
	int a = 0;
	float b = 0.0f;
	scanf("%d %f", &a, &b);
	printf("%d %f\n", a, b);

	return 0;
}



int main()
{
	char c1 = 0;
	char c2 = 0;
	char c3 = 0;
	scanf(" %c%c%c", &c1, &c2, &c3);

	printf("%c %c %c", c1, c2, c3);
	
	return 0;
}




int main()
{
	char arr1[20] = "xxxxxxxxxxxxxxxxx";
	char arr2[20] = "xxxxxxxxxxxxxxxxx";

	scanf("%s %s", arr1, arr2);//这里没有写&arr,为什么呢？因为数组名arr就是地址
	printf("%s %s\n", arr1, arr2);

	return 0;
}


int main()
{
	char arr[5] = { 0 };
	scanf("%4s", arr);
	printf("%s\n", arr);

	return 0;
}



int main()
{
	int a = 0;
	scanf("%d", &a);
	printf("a = %d\n", a);
	return 0;
}

int main()
{
	int year = 0;
	int month = 0;
	int day = 0;

	scanf("%d %d %d", &year, &month, &day);

	printf("%d-%d-%d\n", year, month, day);
	return 0;
}

int main()
{
	int year = 0;
	int month = 0;
	int day = 0;

	scanf("%d%*c%d%*c%d", &year, &month, &day);//2024-1-20

	printf("%d-%d-%d\n", year, month, day);
	return 0;
}

C语言代码练习（test_1_20）