A simple tutorial suitable for beginners to get started with C language
CDeclaration of language data variables
The declaration of integer variables uses int, such as: int a;
The declaration of single-precision floating point types uses float, such as: float b;
Use double to declare double-precision floating point type, such as: double c;
CBasic input and output of language
Use scanf() to input data from the keyboard,
The calling format is: scanf(“%d”, &a);scanf(“%f”, &b);scanf(“%lf”, &c) ;
Use printf() to output data to the screen
The calling format is: printf(“%d %f %lf”,a,b,c);
Output “hello world”
#include<stdio.h> int main() { printf("hello world"); return 0; }
Simple numerical calculation:
#include<stdio.h> //包含一个头文件stdio.h以完成程序的基本输入输出 int main() //程序主函数,每个程序必须要有的部分 { //语句框,表示框内的语句属于主函数,在主函数声明的变量只在主函数内部有效 int a,a1=1; //声明整形变量a和a1,并直接给a1赋初值为1(使用任何变量都必须先声明后使用) a=2; //给声明过的整形变量a赋值为2 float b,b1=1.5; //声明单精度浮点类型变量b和b1,并直接给b1赋初值为1.5 b=3.5; //给声明过的单精度浮点数b赋值为3.5 double c,c1=2.5; //声明双精度浮点类型变量c和c1,并直接给c1赋初值为2.5 c=4.5; //给声明过的双精度浮点数c赋值为4.5 double d=a+b+c+a1+b1+c1; //声明一个双精度浮点数d,并把a+b+c+a1+b1+c1的值赋给d printf("%lf",d); //输出d scanf("%d %f %lf",&a,&b,&c); //从键盘上输入三个值,并分别重新赋给a,b,c,其中%d %f %lf称为占位符,其分别为整型、单精度浮点型、双精度浮点型的占位符表示形式 printf("%d %f %lf",a,b,c); //输出a,b,c return 0; //主函数(main函数)结束的标志 }
The difference between single-precision floating-point number (float) and double-precision floating-point number (double):
01.The number of bytes occupied in the memory is different
Single-precision floating-point numbers occupy 4 bytes in the machine’s memory
Double-precision floating-point numbers occupy in the machine’s memory 8 bytes
02.The number of significant digits is different
Single precision floating point number valid digits8digits
Double precision floating point number valid digits 16bit
03.Value range
The representation range of single-precision floating-point numbers: -3.40E 38~3.40E 38
Double-precision floating-point numbers The representation range: -1.79E 308~-1.79E 308
04. in the program Processing speeds vary
Generally speaking,CPUprocesses single-precision floating-point numbers faster than double-precision floating-point numbers
Thank you all for reading, I hope you will benefit a lot.
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