复习巩固提高
- C语言的基本书写规则：（1）语句以“;”结束；（2）main函数是程序入口，每个应用程序有且只有一个main函数；（3）括号必须前后对应；（4）一般一个语句一行。
- 标识符 程序中的名字。必须以字母或者下划线开头，可以包含字母、下划线、数字，区分大小写。注意避开关键字：
auto,break,case,char,const,continue,default,do,double,else,enum,extern,float,for,goto,if,int,long,register,return,short,signed,sizeof,static,struct,switch,typedef,unsigned,union,void,volatile,while,_Bool,_Complex,_Imaginary,inline,restrict,_Alignas,_Alignof,_Atomic _Generic,_Noreturn,_Static_assert,_Thread_local。 - C语言中的基本变量类型：
int,float,double,char。不常用void。新增auto。扩展类型后续学习。 - 输入输出函数：
scanf()，printf()。 - 引用库——包含头文件:
#include <>,#include ""。 - 扩展练习 计算三角函数。
#include
#include
int main()
{
float jiaoDu, huDu; //用于存储角度
float sinF, cosF, tanF; //用于存储结果
const float PI = 3.1415926; //作为常数π
printf("请输入一个角度："); //提示用户输入
scanf("%f", &jiaoDu); //读入用户输入
huDu = PI * jiaoDu / 180; //将角度转换为弧度
sinF = sin(huDu); //计算正弦函数
cosF = cos(huDu); //计算余弦函数
tanF = tan(huDu); //计算正切函数
printf("sin(%f) = %f\n", jiaoDu, sinF); //输出正弦函数结果
printf("cos(%f) = %f\n", jiaoDu, cosF); //输出余弦函数结果
printf("tan(%f) = %f\n", jiaoDu, tanF); //输出正切函数结果
// 下面的代码是限制小数位数输出的
printf("sin(%1.2f) = %1.3f\n", jiaoDu, sinF);
printf("cos(%1.2f) = %1.3f\n", jiaoDu, cosF);
printf("tan(%1.2f) = %1.3f\n", jiaoDu, tanF);
return 0;
}
运算符与格式化输出
运算符
- 算术运算符
+,-,*,/,%（取余）,++（自增1）,--（自减1）。 - 关系运算符
==（等于）,!=（不等于）,>,>=,<,<= - 逻辑运算符
&&（与）,||（或）,!（非）。 - 位运算符
&,|,^（位异或）,~（位取反）,<<（位左移）,>>（位右移）。 - 赋值运算符
=,+=,-=,*=,/=,%=,<<=,>>=,&=,|=,^= - 杂项运算符
sizeof()（返回变量所占内存大小）,&（递址符）,*（指针）,?:（条件表达式）。
格式化输出
- 各种数据的格式化输出
%d十进制有符号整数占位符，%u十进制无符号整数，%f小数占位符，%c字符占位符，%s字符串占位符，%e指数形式的浮点数占位符，%x、%X无符号以十六进制表示的整数，%g自动选择合适的表示法 - 位宽与小数数量与对齐
%和类型符号中间的第一组数为位宽，.后的数位小数宽度。位宽前加-为左对齐。 - 特殊字符
\n换行，\f清屏并换页，\r回车，\t制表符。
算术运算符练习
#include
int main()
{
int a = 21;
int b = 10;
int c;
printf("a = %d, b = %d\n", a, b);
c = a + b;
printf("a + b = %d\n", c);
c = a - b;
printf("a - b = %d\n", c);
c = a * b;
printf("a * b = %d\n", c);
c = a / b;
printf("a / b = %d\n", c);
c = a % b;
printf("a %% b = %d\n", c);
a++;//a自增1
printf("a++ = %d\n", a);
b--;//b自减1
printf("b-- = %d\n", b);
return 0;
}
关系运算练习
#include
//下面这个函数的作用是返回真（T）假（F）
char isTrue(int v)
{
if (v)
return 'T';
else
return 'F';
}
int main()
{
int a = 21;
int b = 0;
int c = -1;
char d = 'T';
float e = 3.14;
double f = 0.02;
int r;
printf("a = %d\tb=%d\tc=%d\td=%c\te=%f\tf=%f\n\n", a, b, c, d, e, f);
//下面的例子说明了各类类型的数据与布尔数据的对应关系
printf("各类类型的数据与布尔数据的对应关系:\n");
printf("a = %c\n", isTrue(a));
printf("b = %c\n", isTrue(b));
printf("c = %c\n", isTrue(c));
printf("d = %c\n", isTrue(d));
printf("e = %c\n", isTrue(e));
printf("f = %c\n", isTrue(f));
printf("数据比较:\n");
r = a == b;
printf("a = b ? %c\n", isTrue(r));
r = a >= b;
printf("a >= b ? %c\n", isTrue(r));
r = a > b;
printf("a > b ? %c\n", isTrue(r));
r = a <= b;
printf("a <= b ? %c\n", isTrue(r));
r = a < b;
printf("a < b ? %c\n", isTrue(r));
r = a != b;
printf("a != b ? %c\n", isTrue(r));
return 0;
}
逻辑运算符练习
#include
int main()
{
int a = 999;
int b = 0;
printf("a = %d\tb=%d\n\n", a, b);
printf("a && b = %d\n", a && b);
printf("a || b = %d\n", a || b);
printf("!a = %d\n", !a);
printf("!b = %d\n\n", !b);
int i = 5, j = 8, k = 10, r;
printf("i = %d\tj = %d\tk = %d\n", i, j, k);
r = (i + j) > k && k > j;
printf("i + j > k 且 k > j ? %d",r);
return 0;
}
位运算符练习
#include
int main()
{
int a = 3;
int b = 8;
int c;
printf("a = %d\tb = %d\n\n", a, b);
c = a & b;
printf("a & b = %d\n", c);
c = a | b;
printf("a | b = %d\n", c);
c = a ^ b;
printf("a ^ b = %d\n", c);
c = ~a;
printf("~a = %d\n", c);
c = a << 2;
printf("a << 2 = %d\n", c);
c = a >> 1;
printf("a >> 1 = %d\n", c);
return 0;
}
赋值运算符练习
#include
int main()
{
int a = 3;
int b = 8;
int c;
printf("a = %d\tb = %d\n\n", a, b);
printf("a += b = %d\n", a += b);
printf("a -= b = %d\n", a -= b);
printf("a *= b = %d\n", a *= b);
printf("a /= b = %d\n", a /= b);
printf("a %= b = %d\n", a %= b);
return 0;
}
杂项运算符练习
#include
int main()
{
int a = 3;
int b = 8;
char c = 'k';
float f = 0.618;
double d = 2019.0415;
printf("a = %d\tb = %d\tc = %c\tf = %f\td = %f\n\n", a, b, c, f, d);
printf("a = %8d\n", a);
printf("b = %8d\n", b);
printf("b = %-8d\n", b);
printf("c = %8d\n", c);
printf("f = %8.3f\n", f);
printf("d = %8.2f\n", d);
printf("d = %g\n\n", d);
printf("size of a :%d\n", sizeof(a));
printf("size of c :%d\n", sizeof(c));
printf("size of f :%d\n", sizeof(f));
printf("size of d :%d\n\n", sizeof(d));
c = a > b ? 'T' : 'F';
printf("a > b ?\t%c\n", c);
c = a < b ? 'T' : 'F';
printf("a < b ?\t%c\n", c);
return 0;
}