From 442a49ad5a48d417345959b903ae6a6d32d55759 Mon Sep 17 00:00:00 2001
From: Haidong Ji
Date: Fri, 15 Apr 2022 15:51:30 -0500
Subject: Great C programming fun

Excellent fundamentals and displine training, many tools and techniques
exercises: gdb, emacs, valgrind, git
---
 27_matrix_input/rotateMatrix.c | 79 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 27_matrix_input/rotateMatrix.c

(limited to '27_matrix_input/rotateMatrix.c')

diff --git a/27_matrix_input/rotateMatrix.c b/27_matrix_input/rotateMatrix.c
new file mode 100644
index 0000000..8697a0d
--- /dev/null
+++ b/27_matrix_input/rotateMatrix.c
@@ -0,0 +1,79 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define LINE_SIZE 12
+
+void rotate(char matrix[10][10]) {
+  int layer = 0;
+  char temp1;
+  char temp2;
+  char temp3;
+
+  while (layer <= 10 / 2) {
+    for (int i = layer; i < 10 - 1 - layer; i++) {
+      temp1 = matrix[i][10 - 1 - layer];
+      temp2 = matrix[10 - 1 - layer][10 - 1 - i];
+      temp3 = matrix[10 - 1 - i][layer];
+
+      matrix[i][10 - 1 - layer] = matrix[layer][i];
+      matrix[10 - 1 - layer][10 - 1 - i] = temp1;
+      matrix[10 - 1 - i][layer] = temp2;
+      matrix[layer][i] = temp3;
+    }
+    layer++;
+  }
+}
+
+int main(int argc, char **argv) {
+  if (argc != 2) {
+    fprintf(stderr, "Usage: rotateMatrix inputFileName\n");
+    return EXIT_FAILURE;
+  }
+
+  FILE *f = fopen(argv[1], "r");
+  if (f == NULL) {
+    fprintf(stderr, "Could not open file\n");
+    return EXIT_FAILURE;
+  }
+  char line[LINE_SIZE];
+  char matrix[10][10];
+  int lineNumber = 0;
+  while (fgets(line, LINE_SIZE, f) != NULL) {
+    if (lineNumber >= 10) {
+      fprintf(stderr, "Too many lines!\n");
+      return EXIT_FAILURE;
+    }
+    if (strchr(line, '\n') == NULL) {
+      fprintf(stderr, "Line is too long!\n");
+      return EXIT_FAILURE;
+    }
+    if ((strchr(line, '\n') - line) != 10) {
+      fprintf(stderr, "Line is too short!\n");
+      return EXIT_FAILURE;
+    }
+    for (int j = 0; j < 10; j++) {
+      if (line[j] == '\n') {
+        fprintf(stderr, "Line is too short!\n");
+        return EXIT_FAILURE;
+      }
+      matrix[lineNumber][j] = line[j];
+    }
+    lineNumber++;
+  }
+
+  if (lineNumber != 10) {
+    fprintf(stderr, "Not enough number of lines\n");
+    return EXIT_FAILURE;
+  }
+
+  rotate(matrix);
+  for (int i = 0; i < 10; i++) {
+    for (int j = 0; j < 10; j++) {
+      printf("%c", matrix[i][j]);
+    }
+    printf("\n");
+  }
+
+  return EXIT_SUCCESS;
+}
-- 
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