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The NS_StringSetDataRange function copies data into a section of the string's internal buffer. This is a low-level API.

  #include "nsStringAPI.h"

  nsresult NS_StringSetDataRange(
    nsAString& aString,
    PRUint32 aCutStart,
    PRUint32 aCutLength,
    const PRUnichar* aData,
    PRUint32 aDataLength = PR_UINT32_MAX


[in] A nsAString instance to modify.
[in] The starting index of the section to replace, measured in storage units.
[in] The length of the section to replace, measured in storage units.
[in] A raw character array to copy into this string.
[in] The length of aData, measured in storage units. If equal to PR_UINT32_MAX, then aData is assumed to be null-terminated. Otherwise, aData need not be null terminated.

Return Values

The NS_StringSetDataRange function returns NS_OK if successful. Otherwise, it returns an error code.

Example Code

  // Replace all occurances of |matchVal| with |newVal|

  void ReplaceSubstring(nsAString& str,
                        const nsAString& matchVal,
                        const nsAString& newVal)
    const PRUnichar* sp, *mp, *np;
    PRUint32 sl, ml, nl;
    sl = NS_StringGetData(str, &sp);
    ml = NS_StringGetData(matchVal, &mp);
    nl = NS_StringGetData(newVal, &np);
    for (const PRUnichar* iter = sp; iter <= sp + sl - ml; ++iter)
      if (memcmp(iter, mp, ml) == 0)
        PRUint32 offset = iter - sp;
        NS_StringSetDataRange(str, offset, ml, np, nl);
        sl = NS_StringGetData(str, &sp);
        iter = sp + offset + nl - 1;


This function was frozen for Mozilla 1.7. See bug 239123 for details.

See Also


Document Tags and Contributors

Contributors to this page: Sheppy, Pmash
Last updated by: Sheppy,