新增韦东山文件IO内容

C13-Linux系统编程/fs/W_process_excel.c

@@ -0,0 +1,205 @@
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#if 1
+#    define debug(fmt, args...) printf(fmt, ##args)
+#else
+#    define debug(fmt, args...)
+#endif
+
+/**
+ * @brief    读取一行
+ * @details
+ *           循环读入一个字符
+ *           如何判断读完一行? 读到0x0d, 0x0a
+ *
+ * @param    fd
+ * @param    buf
+ *
+ * @return  int 读到的一行数据的数据个数( n>=0 )
+ *              -1: 读到文件尾部或者出错
+ */
+static int read_line(int fd, unsigned char *buf)
+{
+    unsigned char c;
+    int           len;
+    int           i   = 0;
+    int           err = 0;
+
+    while (1)
+    {
+        len = read(fd, &c, 1);
+        if (len <= 0)
+        {
+            err = -1;
+            break;
+        }
+        else
+        {
+            if (c != '\n' && c != '\r')
+            {
+                buf[i] = c;
+                i++;
+            }
+            else /* 碰到回车换行 */
+            {
+                err = 0;
+                break;
+            }
+        }
+    }
+
+    buf[i] = '\0';
+
+    if (err && (0 == i))
+        /* 读到文件尾部且无有效数据 */
+        return -1;
+    else
+        return i;
+}
+
+/**
+ * @brief    处理一行的数据, 计算出总分和评价
+ * @details
+ *
+ * @param    data_buf
+ * @param    result_buf
+ *
+ * @return  int
+ */
+static void process_data(unsigned char *data_buf, unsigned char *result_buf)
+{
+    /**
+     *   eg1: data_buf=",语文,数学,英语,总分,评价"
+     *      result_buf=",语文,数学,英语,总分,评价"
+     *
+     *   eg2: data_buf="张三,90,91,92,,"
+     *      result_buf="张三,90,91,92,273,A+"
+     *
+     */
+
+    char  name[100];
+    int   scores[3];
+    int   sum;
+    char *levels[] = {"A+", "A", "B"};
+    int   level;
+
+    // debug("data_buf[0]: %x\n", data_buf[0]);
+    if (0xef == data_buf[0]) /* 对于UTF-8, 前三个字符是0xef 0xbb 0xbf */
+    {
+        strcpy(result_buf, data_buf);
+    }
+    else
+    {
+        // debug("data_buf: %s\n", data_buf);
+        // debug("进入了\n");
+        /**
+         * @brief    从字符串得到数据
+         * @details
+         *           拆分信息: scanf分隔符
+         *           %[^,]: 读数据直到碰到逗号
+         *
+         */
+        sscanf(data_buf,
+               "%[^,],%d,%d,%d,,",
+               name,
+               &scores[0],
+               &scores[1],
+               &scores[2]);
+
+        debug("name: %s, scores: %d, %d, %d\n",
+              name,
+              scores[0],
+              scores[1],
+              scores[2]);
+
+        sum = scores[0] + scores[1] + scores[2];
+        if (sum >= 270)
+            level = 0;
+        else if (sum >= 240)
+            level = 1;
+        else
+            level = 2;
+
+        sprintf(result_buf,
+                "%s,%d,%d,%d,%d,%s",
+                name,
+                scores[0],
+                scores[1],
+                scores[2],
+                sum,
+                levels[level]);
+    }
+}
+
+
+/**
+ * @brief    处理csv表格
+ * @details
+ *           Usage: ./W_process_excel data.csv result.csv
+ *
+ * @param    argc
+ * @param    argv
+ *
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    int           fd_data, fd_result;
+    int           len;
+    unsigned char data_buf[1000];
+    unsigned char result_buf[1000];
+
+    if (argc != 3)
+    {
+        printf("Usage: %s data.csv result.csv\n", argv[0]);
+        exit(1);
+    }
+
+    fd_data = open(argv[1], O_RDONLY);
+    if (fd_data < 0)
+    {
+        perror("open data.csv");
+        exit(1);
+    }
+    else
+        printf("data file fd: %d\n", fd_data);
+
+    fd_result = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644);
+    if (fd_result < 0)
+    {
+        perror("open result.csv");
+        exit(1);
+    }
+    else
+        printf("result file fd: %d\n", fd_result);
+
+    while (1)
+    {
+        /* 读取1行 */
+        len = read_line(fd_data, data_buf);
+        if (-1 == len)
+            break;
+
+        // if (len != 0)
+        //     debug("%s\n\r", data_buf);
+
+        if (len != 0)
+        {
+            /* 处理1行 */
+            process_data(data_buf, result_buf);
+
+            /* 写入结果文件 */
+            write(fd_result, result_buf, strlen(result_buf));
+            write(fd_result, "\r\n", 2);
+        }
+    }
+
+    close(fd_data);
+    close(fd_result);
+
+    exit(0);
+}