Reverse words function.

assembly/cmd

@@ -0,0 +1,3 @@
+display/10i $eip
+
+break main

experiments/reverse_words.c

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+#include "assert.h"
+#include "stdbool.h"
+#include "stdio.h"
+#include "stdlib.h"
+#include "string.h"
+
+bool reverseWords(char str[]);
+
+int main(int argc, char **argv) {
+  char *s1 = "My kingdom for a horse.";
+  reverseWords(s1);
+  printf("%s\n", s1);
+
+  return 0;
+}
+
+ bool reverseWords(char str[]) {
+  char *buffer;
+  int slen, tokenBegin, tokenEnd, writePos, copyPos;
+
+  slen = strlen(str);
+
+  buffer = (char *)malloc(slen + 1);
+  if (! buffer)
+    return false;
+
+  tokenBegin = tokenEnd = slen - 1;
+  writePos = copyPos = 0;
+
+  while (tokenBegin >= 0) {
+    if (str[tokenBegin] == ' ') {
+      buffer[writePos++] = str[tokenBegin--];
+    } else {
+      while (tokenBegin >= 0 && str[tokenBegin] != ' ')
+        --tokenBegin;
+      copyPos = tokenBegin + 1;
+      while (copyPos <= tokenEnd)
+        buffer[writePos++] = str[copyPos++];
+    }
+  }
+
+  buffer[writePos] = '\0';
+  strlcpy(str, buffer, slen + 1);
+  free(buffer);
+
+  return true;
+}
+
+//bool reverseWords(char str[]) {
+//  char *buffer;
+//  int slen, tokenReadPos, wordReadPos, wordEnd, writePos = 0;
+//  slen = strlen(str);
+//  /* Position of the last character is length - 1 */
+//  tokenReadPos = slen - 1;
+//  buffer = (char *)malloc(slen + 1);
+//
+//  if (!buffer) return false; /* reverseWords failed */
+//  while (tokenReadPos >= 0) {
+//    if (str[tokenReadPos] == ' ') { /* Non-word characters */
+//                                    /* Write character */
+//      buffer[writePos++] = str[tokenReadPos--];
+//    } else { /* Word characters */
+//             /* Store position of end of word */
+//      wordEnd = tokenReadPos;
+//      /* Scan to next non-word character */
+//      while (tokenReadPos >= 0 && str[tokenReadPos] != ' ') tokenReadPos--;
+//      /* tokenReadPos went past the start of the word */
+//      wordReadPos = tokenReadPos + 1;
+//      /* Copy the characters of the word */
+//      while (wordReadPos <= wordEnd) {
+//        buffer[writePos++] = str[wordReadPos++];
+//      }
+//    }
+//  }
+//  /* null terminate buffer and copy over str */
+//  buffer[writePos] = '\0';
+//  strlcpy(str, buffer, slen + 1);
+//  free(buffer);
+//  return true; /* ReverseWords successful */
+//}