Function realloc () in C
The realloc () function attempts to recover the memory block pointed to by the ptr pointer that was previously allocated with a call to malloc or calloc.
Declare the function realloc () in C
Below is the declaration for realloc () in C:
void * realloc ( void * ptr , kich - co )
Parameters
ptr : This is the pointer to the previously allocated memory block with malloc , calloc or realloc to be re-allocated. If the value is NULL, a new block is allocated and a pointer to it is returned by this function.
kich-co : This is the new size for the memory block. If the value is 0 and the pointer ptr points to an existing memory block, the memory block pointed to by ptr is freed and a NULL pointer is returned.
Returns the value
This function returns a pointer to the newly allocated memory, or returns NULL if the request fails.
For example
The following C program illustrates the usage of realloc () in C:
#include #include #include int main () { char * str ; /* lan cap phat bo nho ban bau */ str = ( char *) malloc ( 15 ); strcpy ( str , "QTM" ); printf ( "Chuoi = %s, tai Dia chi = %un" , str , str ); /* tai cap phat lai bo nho */ str = ( char *) realloc ( str , 25 ); strcat ( str , "@gmail.com" ); printf ( "Chuoi = %s, tai Dia chi = %un" , str , str ); free ( str ); return ( 0 ); }
Compile and run the above C program to see the results.
According to Tutorialspoint
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