Diff: strings.cpp

Revision:

0:e0b964252a05

Child:

1:d5452e398b76

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/strings.cpp	Wed May 19 12:39:18 2010 +0000
@@ -0,0 +1,84 @@
+/*******************************************************************************
+
+Strings.cpp - By Sophie Dexter, April 2010
+
+This C++ module provides functions for working with 'strings' of ascii 'char's
+
+C++ should have functions like these, but it doesn't seem to so these are my
+own ones. They are very simple and do not check for any errors e.g. StrCpy
+does not check that s1 is big enough to store all of s2.
+
+********************************************************************************
+
+WARNING: Use at your own risk, sadly this software comes with no guarantees.
+This software is provided 'free' and in good faith, but the author does not
+accept liability for any damage arising from its use.
+
+*******************************************************************************/
+#include "strings.h"
+
+// copies a string, s2, (array of chars) to another string, s1.
+char *StrCpy(char *s1, char *s2) {
+//    while (*s1++ = *s2++);
+    while (*s2)
+        *s1++ = *s2++;
+    return s1;
+}
+
+// returns the number of chars in a string
+int StrLen(char *s) {
+    int x = 0;
+    while (*s++)
+        x++;
+    return (x);
+}
+
+// checks s1 to see if it the same as s2
+// returns TRUE if there is a match
+// WARNING actually only checks that s1 starts with s2!
+bool StrCmp(char *s1, char *s2) {
+//    while (*s2 != '\0') {
+    while (*s2) {
+        if (*s1++ != *s2++) {
+            return FALSE;
+        }
+    }
+    return TRUE;
+}
+
+// Converts lower case ascii letters a-z to upper case
+// leaves other characters unchanged
+char ToUpper(char c) {
+    if (c >= 'a' && c <= 'z')
+        c -= 32;
+    return c;
+}
+
+// Converts upper case ascii letters A-Z to lower case
+// leaves other characters unchanged
+char ToLower(char c) {
+    if (c >= 'A' && c <= 'Z')
+        c += 32;
+    return c;
+}
+
+// Converts ASCII numbers 0-9 and letters a-f (and A-F) to hex values 0x00-0x0F
+// leaves other characters unchanged
+// ASCII '0' is worth 0x30 so subtract 0x30 if ascii character is a number
+// Lower case ASCII letter 'a' is worth 0x61, but we want this to be worth 0x0A
+// Subtract 0x57 (0x61 + 0x0A = 0x57) from lower case letters
+// Upper case ASCII letter 'A' is worth 0x41, but we want this to be worth 0x0A
+// Subtract 0x37 (0x41 + 0x0A = 0x37) from upper case letters
+
+char *aToh(char *s) {
+    while (*s) {
+        if ((*s >= '0') && (*s <='9'))
+            *s -= '0';
+        else if ((*s >= 'a') && (*s <='f'))
+            *s -= ('a' - 0x0A);
+        else if ((*s >= 'A') && (*s <='F'))
+            *s -= ('A' - 0x0A);
+        s++;
+    }
+    return s;
+}
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