init commit

3sem/seminars/l3/04.c

@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/file.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+int
+main(int argc, char *argv[])
+{
+    int fdin = open(argv[1], O_RDONLY);
+    if (fdin == -1) {
+        return 1;
+    }
+
+    unsigned int res = 0, tmp;
+    unsigned char num[4]; // не пишем в int, т.к. неизвестно, какой порядок байтов
+
+    while (read(fdin, num, 4) == 4) {
+        // unsigned int tmp = (unsigned int) num << 24 | (unsigned int) num <<
+        // 16 |
+        //                    (unsigned int) num << 8 | (unsigned int) num;
+        for (int i = 0; i < 4; i++) {
+            tmp = tmp << 8 | num[i];
+        }
+        res += tmp;
+    }
+
+    printf("%u\n", res);
+
+    close(fdin);
+
+    return 0;
+}