C语言入门课程学习笔记2

C语言入门课程学习笔记2

• 第8课 - 四则运算与关系运算
• 第9课 - 逻辑运算与位运算
• 第10课 - 深度剖析位运算
• 第11课 - 程序中的选择结构

本文学习自狄泰软件学院 唐佐林老师的 C语言入门课程，图片全部来源于课程PPT，仅用于个人学习记录

第8课 - 四则运算与关系运算

#include <stdio.h>

int main()
{
    int a = 5;
    int b = 2;
    double c = 3;

    c = a / b;

    printf("c = %f\n", c);

    c = a % b;

    printf("c = %f\n", c);

    return 0;
}

    /*
    output:
c = 2.000000
c = 1.000000
    */

#include <stdio.h>

int main()
{
    int a = 1;
    int b = 2;
    int c = 3;

    c = a != b;//1

    c = a - b >= a + b;//-1>=3    0

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

    c = (a < b) + (c < b);//1<2   0<2    2

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

    return 0;
}




    /*
    output:
c = 0
c = 2
    */

#include <stdio.h>

int main()
{
    int a = 1;
    int b = 2;
    int c = 0;

    c = a != b+a*b;//1!=3  1



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

    c = a == b < c== b;//0<0   0

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

    return 0;
}




    /*
    output:
c = 1
c = 0
    */

第9课 - 逻辑运算与位运算

#include <stdio.h>

int main()
{
    int a = 1;
    int b = 2;
    int c = 0;

    c = a && b;   1&&2   1

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

    c = !(a - b) || (c < b);   !(-1)||(0<2)     0||1    1

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

    c = 10000;
    c = !!c;

    printf("c = %d\n", c);   !0    1

    return 0;
}




    /*
    output:
c = 1
c = 1
c = 1
    */

#include <stdio.h>

int main()
{
    printf("c = %d\n", 5 | 2);      //101|10     111    7
    printf("c = %d\n", 7 ^ 8);      //111^1000    1111   15
    printf("c = %d\n", 2 ^ 3);       //10^11      01     1
    printf("c = %d\n", (15 >> 2) & 13);  //11&1101        1
    printf("c = %d\n", 173 ^ 60);     //1010 1101^0011 1100     1001  0001    145

    return 0;
}




    /*
    output:
c = 7
c = 15
c = 1
c = 1
c = 145
    */

第10课 - 深度剖析位运算

#include <stdio.h>

int main()
{
    short a = 1;
    short b = 2;
    int c = a - b;//-1    1111 1111 1111  1111 1111 1111 1111  1111

    c = c >> 4;//  -1

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

    c = c * -1 * 16 >> 4; //... ...  0001 0000     1

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

    printf("c = %d\n", 16 << 2);  //64

    return 0;
}




    /*
    output:
c = -1
c = 1
c = 64
    */

#include <stdio.h>

int main()
{
    char c = 'A';
    short a = c;
    int b = c;

    printf("c = %c\n", c);//A
    printf("c = %d\n", c);//65
    printf("a = %d\n", a);//65
    printf("b = %d\n", b);//65

    c = 0x40;

    printf("c = %x\n", c);//40
    printf("c = %d\n", c);//64

    c = c << 1;

    printf("c = %d\n", c);//1000 0000    -128

    c = c << 1;

    printf("c = %d\n", c);//   0000 0000    0

    return 0;
}




    /*
    output:
c = A
c = 65
a = 65
b = 65
c = 40
c = 64
c = -128
c = 0
    */

补充点：原码、反码及补码，十进制、二进制、十六进制之间的转换

第11课 - 程序中的选择结构

#include <stdio.h>

int main()
{
    short a = 1;
    short b = 2;
    int c = a - b;

    if( c > 0 )
    {
        printf("a > b\n");
    }
    else
    {
        printf("a <= b\n");
    }

    return 0;
}




    /*
    output:
a <= b
    */

#include <stdio.h>

int main()
{
    short a = 2;
    short b = 2;
    int c = a - b;

    if( c > 0 )
        printf("a > b\n");
    else if( c == 0 )
        printf("a == b\n");
    else
        printf("a < b\n");

    return 0;
}




    /*
    output:
a == b
    */