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Full Discussion: Pointer to pointers
Top Forums Programming Pointer to pointers Post 302572374 by pharaoh on Wednesday 9th of November 2011 08:38:09 PM
Old 11-09-2011
Pointer to pointers

Hi guys, I'm trying to understand pointers in C and made a simple example and I've problems with It.
Can someone help?

Code:
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

int f1(char **str_);

int main(int argc, char **argv)
{
    char *str = NULL;

    f1(&str);     
    printf("str : %s\n", *str);

    str = realloc(str, (size_t) 0);   
    assert(str == NULL);

    return 0;
}

int f1(char **str_)
{
    if ((*str_ = realloc(*str_, sizeof(char) * 12)) == NULL)
    {
        fprintf(stderr,"realloc() failed\n");
        exit(3);
    }

    (*str_) = "hello there";

    return 0;
}

Thanks in advance.
 

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curs_instr(3X)															    curs_instr(3X)

NAME
instr, innstr, winstr, winnstr, mvinstr, mvinnstr, mvwinstr, mvwinnstr - get a string of characters from a curses window SYNOPSIS
#include <curses.h> int instr(char *str); int innstr(char *str, int n); int winstr(WINDOW *win, char *str); int winnstr(WINDOW *win, char *str, int n); int mvinstr(int y, int x, char *str); int mvinnstr(int y, int x, char *str, int n); int mvwinstr(WINDOW *win, int y, int x, char *str); int mvwinnstr(WINDOW *win, int y, int x, char *str, int n); DESCRIPTION
These routines return a string of characters in str, extracted starting at the current cursor position in the named window. Attributes are stripped from the characters. The four functions with n as the last argument return a leading substring at most n characters long (exclu- sive of the trailing NUL). RETURN VALUE
All of the functions return ERR upon failure, or the number of characters actually read into the string. X/Open defines no error conditions. In this implementation, if the window parameter is null or the str parameter is null, a zero is returned. NOTES
Note that all routines except winnstr may be macros. PORTABILITY
SVr4 does not document whether a length limit includes or excludes the trailing NUL. The ncurses library extends the XSI description by allowing a negative value for n. In this case, the functions return the string ending at the right margin. SEE ALSO
curses(3X). curs_instr(3X)
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