C 语言学习-03【输入与输出】

1、复合赋值语句

赋值语句：

#include <stdio.h>

int main() {
    int i = 1, j = 5, m = 4, n = 3;
    j += i;
    m %= n;
    n += n -= n * n;
    printf("j = %d m = %d n = %d\n", j, m, n);
    char a = 'A', b, c;
    c = b = a + 1;
    printf("a = %c b = %c c = %c", a, b, c);
    return 0;
}

• 运行结果：
  

2、字符输入函数 getchar()

getchar() 函数的用法：

#include <stdio.h>

int main() {
    char ch;
    ch = getchar();
    putchar(ch);
    putchar('\n');
    putchar(getchar());
    putchar(getchar());
    putchar('\n');
    putchar('c');
    return 0;
}

• 运行结果：
  

3、字符输出函数 putchar()

putchar() 函数的用法：

#include <stdio.h>

int main() {
    char a = 'H', b = 'e', c = 'I', d = 'I', e = 'o';
    putchar(a);
    putchar(b);
    putchar(c);
    putchar(d);
    putchar(e);
    putchar('\n');
    putchar(a + 1);
    putchar('\n');
    putchar('\101');
    return 0;
}

• 运行结果：
  

4、格式化输入函数 scanf()

scanf() 函数的用法：

#include <stdio.h>

int main() {
    int i = 0;
    char ch = 0;
    float f = 0.0;
    scanf("i = %d, ch = %c, f = %f", &i, &ch, &f);
    printf("The values of the three variables are: \n");
    printf("i = %d, ch = %c, f = %f\n", i, ch, f);
    printf("The address of ch in memory is: %o\n", &ch);
    printf("The address of ch in memory is: %d\n", &ch);
    printf("The address of ch in memory is: %x\n", &ch);
    return 0;
}

• 运行结果：
  

5、d 格式控制字符

格式控制字符 d 的用法：

#include <stdio.h>

int main(void) {
    int i = 123456;
    printf("%d\n", i);
    printf("%5d\n", i);
    printf("%8d\n", i);
    printf("%-8d\n", i);
    return 0;
}

• 运行结果：
  

6、o and x 格式控制字符

格式控制字符 o 和 x 的用法：

#include <stdio.h>

int main(void) {
    int a = 0, b = 1, c = -1;
    printf("%d, %o, %x\n", a, a, a);
    printf("%d, %o, %x\n", b, b, b);
    printf("%d, %o, %x\n", c, c, c);
    return 0;
}

• 运行结果：
  

7、s 格式控制字符

m.ns 和 -m,ns 格式符：

#include <stdio.h>

int main(void) {
    printf("%s\n", "Student");
    printf("%7.3s\n", "Student");
    printf("%-7.3s\n", "Student");
    printf("%3.7s\n", "Student");
    printf("%3.5s\n", "Student");
    return 0;
}

• 运行结果：
  

8、f 格式控制字符

%f、%m.nf 和 %-m.nf 格式符练习

#include <stdio.h>

int main(void) {
    float f1 = 100.110000999;
    float f2 = 100.110000;
    float f3 = 123456.789;
    printf("%f\n", f1);
    printf("%f\n", f2);
    printf("%f\n", f3);
    printf("%10.1f\n", f3);
    printf("%5.1f\n", f3);
    printf("%12.3f****\n", f3);
    printf("%-12.3f****\n", f3);
    return 0;
}

• 运行结果：
  

9、学生基本信息的输入和输出

数据的输入输出综合：

#include <stdio.h>

int main() {
    int id, year, month, day;
    float chinese, math, score;
    char sex;
    printf("Please enter your student number: ");
    scanf("%d", &id);
    getchar();
    printf("Please enter gender (can enter m or f): ");
    sex = getchar();
    printf("Please enter the date (e.g. 2024/11/11): ");
    scanf("%d/%d/%d", &year, &month, &day);
    printf("Please enter your Chinese and math scores separated by Spaces: ");
    scanf("%f %f", &chinese, &math);
    score = chinese + math;
    printf("===========================================\n");
    printf("Student information is shown below: \n");
    printf("Student number: %d\n", id);
    printf("Sex: ");
    putchar(sex);
    printf("\ndate: %d/%d/%d\n", year, month, day);
    printf("chinese: %7.2f\n", chinese);
    printf("math: %-7.2f\n", math);
    printf("total score: %3.4f\n", score);
    return 0;
}

• 运行结果：