优化了命名

C03-输入输出专题/IO/getchar_putchar.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main()
+{
+    int ch;
+    ch = getchar();
+    putchar(ch);
+
+    exit(0);
+}

C03-输入输出专题/IO/gets_puts.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define STRSIZE 32
+
+int main()
+{
+    char str[STRSIZE];
+    gets(str);
+    puts(str);
+
+    exit(0);
+}

C03-输入输出专题/IO/makefile

@@ -0,0 +1,15 @@
+CC=cc
+CFLAGS=
+LDFLAGS=-lm
+TARGET=test
+SRC=test.c
+OBJ=$(SRC:.c=.o)
+
+$(TARGET): $(OBJ)
+	$(CC) -o $@ $^ $(LDFLAGS)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f $(TARGET) $(OBJ)

C03-输入输出专题/IO/printf.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+/***
+ * printf("%[修饰符]格式字符", 输出表项);
+ *
+ */
+
+#define STRSIZE 10
+
+int main()
+{
+    // printf("hello world\n");
+
+    // char ch = 65;
+    // printf("%c\n", ch);
+    // out: A
+
+    int i = 255;
+    float f = 123.45678;
+    char str[STRSIZE] = "helloworld";
+    double dou = 123.456;
+    long long l = 123456;
+    // 不加\n，before while()存入了缓冲区，故不输出
+    // printf("[%s:%d]before while().", __FUNCTION__, __LINE__);
+    printf("[%s:%d]before while().\n", __FUNCTION__, __LINE__);
+    while (1)
+    {
+    }
+    // printf("[%s:%d]after while().", __FUNCTION__, __LINE__);
+    printf("[%s:%d]after while().\n", __FUNCTION__, __LINE__);
+    // printf("f = %8.1f\n", f);
+    // out:f =    123.5
+    // printf("i = %2d\n", i);
+    // out: i = 123
+
+    // printf("%-10.5s[over]\n", str);
+    // printf("%+10.5s[over]\n", str);
+    // out:
+    // hello     [over]
+    //      hello[over]
+
+    // 同样对于i进行八进制核对十六进制的输出
+    //  printf("i = %#o\n", i);
+    //  out: i = 0377
+    //  printf("i = %#x\n", i);
+    //  out: i = 0xff
+
+    // printf("dou = %lf\n", dou);
+    // printf("l = %ld\n", l);
+    // out:
+    // dou = 123.456000
+    // l = 123456
+
+    // printf("hello world!\n");
+    // 实参过多或者过少都会警告
+    // printf("#d #e\n", i);
+    // printf("#d #e\n", i, f, l);
+
+    exit(0);
+}
+
+#if 0
+func(FILE *fp, long i)
+{
+}
+
+int main()
+{
+    FILE *fp;
+    long a = 11;
+
+    fp = fopen();
+
+    // 可行，a定义了long型，与函数要求一致
+    func(fp, a);
+
+    // 早期的编译器不认可，这个12没有单位，不同编译器默认类型不同
+    // 需要加上L修饰符
+    func(fp, 12);
+    func(fp, 12L);
+    // 对于func(FILE *fp, long long i)
+    func(fp, 12LL);
+}
+#endif
+
+// 定义一年有多少秒
+#define SEC_YEAR (60LL * 60LL * 24LL * 365LL)

C03-输入输出专题/IO/scanf.c

@@ -0,0 +1,83 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+/**
+ *  int scanf(const char *format, 地址表);
+ */
+
+// #define STRSIZE 32
+#define STRSIZE 3
+// 除掉尾0占一个
+// 相当于只能两个字符
+// 但是这时候运行输入hello，不会报错
+// 实际上是越界了
+
+int main()
+{
+    int i;
+    float f;
+    char str[STRSIZE];
+    int ret;
+    char ch;
+
+    printf("Please enter:\n");
+
+    // scanf("%d", &i);
+    // ch = getchar();
+
+    // printf("i = %d, ch = %c\n", i, ch);
+    /*
+    out:
+    Please enter:
+    4 h
+    i = 4, ch =
+    ch被吞掉了
+    */
+
+    // scanf("%d", &i);
+    // scanf("%*c%c", &ch);
+    // 用 '%*c' 吃掉回车
+    /*
+    out:
+    Please enter:
+    5
+    h
+    i = 5, ch = h
+    */
+
+    printf("i = %d, ch = %c\n", i, ch);
+
+#if 0
+    // 输入a直接卡死，scanf直接放在循环中很危险
+    // 需要加入校验，用ret接收scanf返回值
+    while (1)
+    {
+        // scanf("%d", &i);
+
+        ret = scanf("%d", &i);
+        if (ret != 1)
+        {
+            printf("Enter Error!\n");
+            break;
+        }
+
+        printf("i = %d\n", i);
+    }
+#endif
+
+    // printf("Please enter fot str:\n");
+    // 这种情况下，不能有任何间隔符
+    // 输入hello world，只会得到hello
+    // 对于scanf，不建议'%s'
+    // scanf("%s", str);
+    // printf("%s\n", str);
+
+    // printf("Please enter for i[int]:\n");
+    // 这里两个数字之间有','，输入就一定要有','
+    // 最好不加，空格符可以是空格 回车 tab
+    // scanf("%d,%f", &i, &f);
+    // printf("i = %d\n", i);
+    // printf("f = %f\n", f);
+
+    exit(0);
+}

C03-输入输出专题/IO/test.c

@@ -0,0 +1,91 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#define WEIGHT 3.0e-23
+#define KQ 950
+
+static void water(void)
+{
+    float num;
+    float sum;
+
+    printf("Please input for num:");
+    scanf("%f", &num);
+
+    if (num <= 0)
+    {
+        fprintf(stderr, "Input Error!\n");
+        exit(1);
+    }
+    sum = num * KQ / WEIGHT;
+
+    printf("Total = %e\n", sum);
+
+    return;
+}
+
+static void area(void)
+{
+    float a, b, c;
+    float s, area;
+
+    printf("Please input:");
+    scanf("%f%f%f", &a, &b, &c);
+    // 对scanf做好校验是好习惯
+    if (a + b <= c || b + c <= a || a + c <= b)
+    {
+        fprintf(stderr, "EINVAL!\n");
+        exit(0);
+    }
+
+    printf("a = %f\n", a);
+    printf("b = %f\n", b);
+    printf("c = %f\n", c);
+
+    // s = 1 / 2 * (a + b + c);
+    s = 1.0 / 2 * (a + b + c);
+    printf("s = %f\n", s);
+    // s=0.000000
+    // 1 / 2是int型计算，得到的是商0余1
+
+    area = sqrt(s * (s - a) * (s - b) * (s - c));
+    printf("area = %f\n", area);
+}
+
+void root(void)
+{
+    float a, b, c;
+    float disc;
+    float p, q;
+    float x1, x2;
+
+    printf("Please input :\n");
+    scanf("%f%f%f", &a, &b, &c);
+
+    if (b * b - 4 * a * c < 0)
+    {
+        fprintf(stderr, "EINVAL\n");
+        exit(1);
+    }
+    disc = b * b - 4 * a * c;
+    p = -b / 2 * a;
+    q = sqrt(disc) / 2 * a;
+
+    x1 = p + q;
+    x2 = p - q;
+
+    printf("x1 = %f\n", x1);
+    printf("x2 = %f\n", x2);
+}
+
+int main()
+{
+    // water();
+
+    // area();
+
+    root();
+
+    exit(0);
+}