/// <summary>
/// returns a copy of <paramref name="str"/> where the characters
/// at the specified <paramref name="indices"/> are set to uppercase,
/// and the rest are set to lowercase.
/// </summary>
/// <param name="str"></param>
/// <param name="indices"></param>
/// <returns>
/// a copy of <paramref name="str"/> where the characters
/// at the specified <paramref name="indices"/> are set to uppercase,
/// and the rest are set to lowercase
/// </returns>
public static string MakeOnlyCharactersAtIndicesUpper(
this string str,
params int[] indices)
{
// assert that all indices are valid
for (int i = 0; i < indices.Length; i++)
{
StringUtils.AssertValidIndexInString(
indices[i],
str,
string.Format("indices[{0}]", i)
);
}
string upperCaseString;
char[] stringCharArray = str.ToCharArray();
// turn all characters to lowercase
for (int i = 0; i < stringCharArray.Length; i++)
{
stringCharArray[i] = char.ToLower(stringCharArray[i]);
}
// make characters at specified indices uppercase
foreach (int index in indices)
{
stringCharArray[index] = char.ToUpper(stringCharArray[index]);
}
upperCaseString = new string(stringCharArray);
return(upperCaseString);
}
/// <summary>
/// returns whether <paramref name="str"/> starts with specified <paramref name="prefix"/>,
/// beginning at specified <paramref name="startIndex"/>.
/// </summary>
/// <param name="str"></param>
/// <param name="startIndex"></param>
/// <param name="prefix"></param>
/// <returns>
/// true if <paramref name="str"/> starts with specified <paramref name="prefix"/>,
/// beginning at specified <paramref name="startIndex"/>,
/// else false
/// </returns>
/// <exception cref="IndexOutOfRangeException">
/// <seealso cref="StringUtils.AssertValidIndexInString(int, string, string)"/>
/// </exception>
public static bool StartsWith(this string str, int startIndex, string prefix)
{
StringUtils.AssertValidIndexInString(startIndex, str, "startIndex");
bool startsWithPrefix;
int curStringIndex;
int curPrefixIndex;
// run through str, starting at startIndex, and compare each of its characters
// with the corresponding character in prefix
for (curStringIndex = startIndex, curPrefixIndex = 0;
curPrefixIndex < prefix.Length && curStringIndex < str.Length;
curStringIndex++, curPrefixIndex++)
{
// mismatch between character in str and its corresponding character in prefix
if (str[curStringIndex] != prefix[curPrefixIndex])
{
break;
}
}
// string starts with prefix (at startIndex)
// iff end of prefix was reached, i.e all characters of prefix and str match
startsWithPrefix = curPrefixIndex == prefix.Length;
return(startsWithPrefix);
}
/// <summary>
/// returns a copy of <paramref name="str"/> where the characters
/// at the specified <paramref name="indices"/> are set to uppercase.
/// </summary>
/// <param name="str"></param>
/// <param name="indices"></param>
/// <returns>
/// a copy of <paramref name="str"/> where the characters
/// at the specified <paramref name="indices"/> are set to uppercase.
/// </returns>
/// <exception cref="IndexOutOfRangeException">
/// <seealso cref="StringUtils.AssertValidIndexInString(int, string, string)"/>
/// </exception>
public static string CharactersAtIndicesToUpper(this string str, params int[] indices)
{
// assert that all indices are valid
for (int i = 0; i < indices.Length; i++)
{
StringUtils.AssertValidIndexInString(
indices[i],
str,
string.Format("indices[{0}]", i)
);
}
char[] stringCharArray = str.ToCharArray();
foreach (int index in indices)
{
stringCharArray[index] = char.ToUpper(stringCharArray[index]);
}
return(new string(stringCharArray));
}
/// <summary>
/// returns the index of the first occurrence of the first expression in
/// specified <paramref name="expressions"/> array which appears in
/// in <paramref name="str"/>. if no expression appears in <paramref name="str"/> returns -1.
/// </summary>
/// <param name="str"></param>
/// <param name="startIndex"></param>
/// <param name="expressions"></param>
/// <param name="chosenExpression">
/// the expression which appears first in specified <paramref name="str"/>
/// </param>
/// <returns>
/// index of the first occurrence of the first expression in
/// specified <paramref name="expressions"/> array which appears in
/// in <paramref name="str"/>,
/// or -1 if no expression appears in <paramref name="str"/>
/// </returns>
/// <exception cref="IndexOutOfRangeException">
/// <seealso cref="StringUtils.AssertValidIndexInString(int, string, string)"/>
/// </exception>
public static int IndexOfAny(
this string str,
int startIndex,
string[] expressions,
out string chosenExpression)
{
StringUtils.AssertValidIndexInString(startIndex, str, "startIndex");
int indexOfFirstOccurrenceOfChosenExpression = int.MaxValue;
chosenExpression = null;
// get the index of the first occurrence of any of the specified expressions
foreach (string expression in expressions)
{
// get index of first occurrence of expression, starting at startIndex
int indexOfNextOccurrenceOfExpressionToOmit = str.IndexOf(
expression,
startIndex);
// first occurrence of expression, starting at startIndex, found in str
if (indexOfNextOccurrenceOfExpressionToOmit != -1)
{
// get the min index of the first expression occurrence between
// all specified expressions
indexOfFirstOccurrenceOfChosenExpression = Math.Min(
indexOfFirstOccurrenceOfChosenExpression,
indexOfNextOccurrenceOfExpressionToOmit);
chosenExpression = expression;
}
}
// no occurrence of any of the specified expressions was found in str
if (indexOfFirstOccurrenceOfChosenExpression == int.MaxValue)
{
indexOfFirstOccurrenceOfChosenExpression = -1;
}
return(indexOfFirstOccurrenceOfChosenExpression);
}