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Full Discussion: Dynamic memory allocation
Top Forums Programming Dynamic memory allocation Post 302230579 by vino on Saturday 30th of August 2008 04:38:14 AM
Old 08-30-2008
Quote:
Originally Posted by naan
Yes, the length of each line.

Suppose I have a file with the lines:
Today is tuesday.
Tomorrow is Wednesday.

I have to find the length of the first line which I can do by character by character reading till I reach a '\n' with a count of the number of characters but then I have to go back to the beginning of the line again to read the contents of the line and put in the buffer which is allocated the number I obtained by the first level of counting.
Why dont you construct a buffer of some size say 1024. Initialize the buffer contents with 0. As you read each character put that character into the buffer. Once the line is done, you have the length as well as the contents. Create your new memory with that length and do a memcpy (destination, source, length) to copy the contents.
 

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XmTextFieldGetSubstringWcs(3X)											    XmTextFieldGetSubstringWcs(3X)

NAME
XmTextFieldGetSubstringWcs - A TextField function that retrieves a portion of a wide character internal text buffer SYNOPSIS
#include <Xm/TextF.h> int XmTextFieldGetSubstringWcs (widget, start, num_chars, buffer_size, buffer) Widget widget; XmTextPosition start; int num_chars; int buffer_size; wchar_t *buffer; DESCRIPTION
XmTextFieldGetSubstringWcs retrieves a copy of a portion of the internal text buffer of a TextField widget that is stored in a wide charac- ter format. The function copies a specified number of characters from a given start position in the internal text buffer into a buffer provided by the application. A NULL terminator is placed at the end of the copied data. Specifies the TextField widget ID. Specifies the beginning character position from which the data will be retrieved. This is an integer number of characters from the beginning of the text buffer. The first character position is 0. Specifies the number of wchar_t characters to be copied into the provided buffer. Specifies the size of the supplied buffer as a number of wchar_t storage locations. The minimum size is num_chars + 1. Specifies the wide character buffer into which the internal text buffer will be copied. For a complete definition of TextField and its associated resources, see XmTextField(3X). RETURN VALUE
The function was successful. The function failed because it was unable to copy the specified number of characters into the buffer pro- vided. The buffer size may be insufficient. The contents of buffer are undefined. The requested number of characters extended beyond the internal buffer. The function copied characters to the end of the buffer and terminated the string with a NULL terminator; fewer than num_chars characters were copied. SEE ALSO
XmTextField(3X), XmTextFieldGetSubstring(3X) XmTextFieldGetSubstringWcs(3X)
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