《C Primer Plus》第三章：数据和C

数据类型-类型匹配符

#include<stdio.h>
int main(void)
{
    unsigned int un = 3000000000;
    short end = 200;
    long big = 65537;
    long long verybig = 12345678908642;

    printf("un = %u and not %d\n", un, un);
    printf("end = %hd and %d\n", end, end);
    printf("big = %ld and not %hd\n", big, big);
    printf("verybig= %lld and not %ld\n", verybig, verybig);

    return 0;
}

un = 3000000000 and not -1294967296
end = 200 and 200
big = 65537 and not 1
verybig= 12345678908642 and not 1942899938

字符类型

#include<stdio.h>
int main(void)
{
    char ch;
    printf("please enter a character.\n");
    scanf_s("%c", &ch);
    printf("the code for %c is %d.\n", ch, ch);

    return 0;
}

please enter a character.
C
the code for C is 67.

可移植类型：stdint.h和inttypes.h

/* altnames.c -- 可移植整数类型名*/
#include <stdio.h>
#include <inttypes.h>   //支持可移植类型
int main(void)
{
    int32_t me32;       // me32是一个32位有符号整型变量
    me32 = 45933945;
    printf("First, assume int32_t is int:");
    printf("me32 = %d\n", me32);
    printf("Next, let's not make money any assumptions.\n");
    printf("Instead, use a \"macro\" form inttypes.h:");
    //在inttypes.h头文件中定义了PRId32字符串宏
    //代表打印32位有符号值的合适转换声明
    printf("me32 = %" PRId32 "\n", me32);

    return 0;
}

浮点数float

/*以两种方式显示float类型的值*/
#include<stdio.h>
int main(void)
{
    float aboat = 32000.0;
    double abet = 2.14e9;
    long double dip = 5.32e-5;

    printf("%f can be written %e\n", aboat, aboat);
    //下列代码要求编译器支持C99或其中相关特性
    printf("And it's %a in hexadecimal, powers of 2 notation\n", aboat);
    printf("%f can be written %e\n", abet, abet);
    printf("%Lf can be writeen %Le\n", dip, dip);

    return 0;
}

32000.000000 can be written 3.200000e+004
And it's 0x1.f40000p+14 in hexadecimal, powers of 2 notation
2140000000.000000 can be written 2.140000e+009
0.000053 can be writeen 5.320000e-005

数据类型的大小

#include<stdio.h>
int main(void)
{
    /*c99为类型大小提供%zd转换说明*/
    printf("Type int has a size of %d bytes.\n", sizeof(int));
    printf("Type char has a size of %d bytes.\n", sizeof(char));
    printf("Type long has a size of %d bytes.\n", sizeof(long));
    printf("Type long long has a size of %d bytes.\n", sizeof(long long));
    printf("Type double has a size of %d bytes.\n", sizeof(double));
    printf("Type long double has a size of %d bytes.\n", sizeof(long double));

    return 0;
}

Type int has a size of 4 bytes.
Type char has a size of 1 bytes.
Type long has a size of 4 bytes.
Type long long has a size of 8 bytes.
Type double has a size of 8 bytes.
Type long double has a size of 8 bytes.

转义序列的使用

字符

#include<stdio.h>
int main(void)
{
    float salary;
    // \a 发出警报  没有换行符，光标停留在：后面
    printf("\aEnter your desired monthly salary:");
    // 7个退格符\b将光标左移7个位置
    printf(" $_______\b\b\b\b\b\b\b");
    scanf_s("%f", &salary);
    // \n换行使光标移动到下一行起始处; \t 水平制表符使光标移至该行的下一个制表点
    printf("\n\t$%.2f a month is $%.2f a year.", salary, salary*12.0);
    // \r使光标回到当前行的起始处，然后打印
    printf("\rGee!\n");
    return 0;
}

Enter your desired monthly salary: $500.2__

Gee!    $500.20 a month is $6002.40 a year.