字符串和格式化输入输出

#include<stdio.h>
int main(void)
{
	int f = 4;
	int g = 5;
	float h = 5.0f;
	
	printf("%d\n", f, g);
	printf("%d %d\n", f);
	printf("%d %f\n", h, g);
	
	return 0;
}

　　上面的代码是错误的。参数不正确。

第四章学习知识点：

函数：

strlen()

关键字：

const

字符串：

如何创建和存储字符串

如何使用scanf()和printf()读取和显示字符串

如何使用strlen()函数获取字符串的长度

使用C预处理器的#define 指令和ANSIC的const修饰符创建符号常量。

遇到strlen函数时计算占的空间大小，sizeof是计算多少个字节。

头文件：string.h

 

　　格式：strlen (字符数组名)

 

　　功能：计算字符串s的(unsigned int型)长度,不包括'\0'在内

 

　　说明：返回s的长度，不包括结束符NULL。

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

#define DENSITY 62.4
int main()
{
	float weight, volume;
	int size,letters;
	char name[40];
	
	printf("Hi! What's your first name?\n");
	scanf("%s", name);
	printf("%s, what's your weight in pounds?\n", name);
	scanf("%f",&weight);
	size = sizeof name;
	letters = strlen(name);
	volume = weight / DENSITY;
	printf("Well, %s, your volume is %2.2f cubic feet.\n", name, volume);
	printf("Also, your first name has %d letters.\n", letters);
	printf("and we have %d bytes to store it in.\n", size);
	return 0;
}

　　上面用到了strlen（）和sizeof

sizeof是关键字。

#include<stdio.h>

#define PI 3.14159
int main(void)
{
	float area, circum, radius;
	
	printf("What is the radius of your pizza?\n");
	scanf("%f", &radius);
	area = PI * radius * radius;
	circum = 2.0 * PI * radius;
	printf("Your basic pizza parameters are as follows:\n");
	printf("circumference = %1.2f, area = %1.2f\n", circum, area);
	return 0;
}

　　

下面这个就是注意PRINTF的参数：

#include<stdio.h>

#define PAGES 931
int main(void)
{
	printf("*%d*\n", PAGES);
	printf("*%2d*\n", PAGES);
	printf("*%10d*\n", PAGES);
	printf("*%-10d*\n", PAGES);
}

　

#include<stdio.h>

int main(void)
{
	const double RENT = 3852.99;
	
	printf("*%f*\n", RENT);
	printf("*%e*\n", RENT);
	printf("*%4.2f*\n", RENT);
	printf("*%3.1f*\n", RENT);
	printf("*%10.3f*\n", RENT);
	printf("*%10.3e*\n", RENT);
	printf("*%10.3e*\n", RENT);
}