Format
#include <string.h>
char *_debug_strcat(char *string1, const char *string2,
const char *filename, size_t line);
Language Level: Extension
_debug_strcat is the debug version of strcat. Like
strcat, it concatenates string2 to string1
and ends the resulting string with the null character.
_debug_strcat validates the heap after concatenating the strings, and performs this check only when the target is within a heap. _debug_strcat makes an implicit call to _heap_check. If _debug_strcat detects a corrupted heap when it makes a call to _heap_check, _debug_strcat will report the file name file and line number line in a message.
Note: _debug_strcat checks only the current default heap. Therefore, this debug support will not check all heaps within applications that have multiple user heaps.
To use _debug_strcat, you must compile with the debug memory (/Tm) compiler option. This option maps all strcat calls to _debug_strcat. You do not have to change your source code, in order for _debug_strcat to verify the heap.
Note: The /Tm option maps all calls to other string functions and all calls to memory management functions (including a heap-specific version), to their debug counterparts. To prevent a call from being mapped, parenthesize the function name.
Return Value
_debug_strcat returns a pointer to the concatenated
string (string1).
Example
This example is similar to the strcat example, except that it
contains a programming error. The buffer1 object is not large
enough to store the result after the string " program"
is concatenated.
#include <stdlib.h> #include <stdio.h> #include <string.h>
#define SIZE 10
int main(void)
{
char *buffer1;
char *ptr;
buffer1 = (char*)malloc(SIZE); strcpy(buffer1, "computer");
ptr = strcat(buffer1, " program");
printf("buffer1 = %s\n", buffer1);
return 0;
/****************************************************************************
The output should be similar to:
End of allocated object 0x00073c80 was overwritten at 0x00073c8a.
The first eight bytes of the memory block (in hex) are: 636F6D7075746572.
This memory block was (re)allocated at line number 12 in strcat.c.
Heap state was valid at line 13 of strcat.c.
Memory error detected at line 15 of strcat.c.
****************************************************************************/
}
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Managing Memory
with Multiple Heaps
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_debug_strncat -- Concatenate Strings
_heap_check -- Validate Default Memory
Heap
strcat -- Concatenate Strings
strncat -- Concatenate Strings
<string.h>
/Tm compiler option