init commit

3sem/seminars/l3/01.c

@@ -0,0 +1,40 @@
+#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[])
+{
+
+    char *fin = argv[1];
+    char *fout = argv[2];
+
+    // printf("fdin: %d\n", fin);
+
+    int fdin = open(fin, O_RDONLY);
+    if (fdin == -1) {
+        return 1;
+    }
+
+    int fdout = open(fout, O_WRONLY | O_CREAT | O_TRUNC, 0777);
+    for (;;) {
+        char c[1024];
+        int r = read(fdin, c, 1024);
+        if (r == -1) {
+            return 1;
+        }
+        if (r == 0) {
+            break;
+        }
+        write(fdout, c, r);
+    }
+
+    close(fdin);
+    close(fdout);
+
+    return 0;
+}

3sem/seminars/l3/02.c

@@ -0,0 +1,52 @@
+#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("in", O_RDWR);
+    if (fdin == -1) {
+        return 1;
+    }
+
+    double num1, num2;
+
+    // Read the first double
+    if (read(fdin, &num1, sizeof(double)) != sizeof(double)) {
+        close(fdin);
+        return 1;
+    }
+
+    // Read the second double
+    if (read(fdin, &num2, sizeof(double)) != sizeof(double)) {
+        close(fdin);
+        return 1;
+    }
+
+    // Move the file pointer back to the beginning
+    if (lseek(fdin, 0, SEEK_SET) == -1) {
+        close(fdin);
+        return 1;
+    }
+
+    // Write the second double first
+    if (write(fdin, &num2, sizeof(double)) != sizeof(double)) {
+        close(fdin);
+        return 1;
+    }
+
+    // Write the first double second
+    if (write(fdin, &num1, sizeof(double)) != sizeof(double)) {
+        close(fdin);
+        return 1;
+    }
+
+    close(fdin);
+
+    return 0;
+}

3sem/seminars/l3/03.с

@@ -0,0 +1,27 @@
+#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 fdout = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0600);
+    if (fdout == -1) {
+        return 1;
+    }
+
+    unsigned short x;
+
+    while (scanf("%hu", &x) == 1) {
+        unsigned char buf[2];
+        buf[0] = x >> 8;
+        buf[1] = x & 0xff;
+        write(fdout, &x, 2);
+    }
+    
+    close(fdout);
+    
+    return 0;
+}

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;
+}

3sem/seminars/l3/out

@@ -0,0 +1 @@
+123 234