hello all,
my question is not about How code can be rewritten, i just wanna know even though i am not using read only memory of C (i have declared str[20]) why this function gives me segfault and the other code executes comfortably though both code uses same pointer arithmetic.
Code:
#include<stdio.h>
#include<string.h>
void reverse(char*);
int
main()
{
char str[20];
scanf("%s",str);
printf("original string is %s :\n",str);
reverse(str);
printf("reverse string is %s :",str);
return 0;
}
void reverse(char* s)
{
int n,mark,temp;
n = mark = strlen(s);
for(;s < (s + n/2);++s)
{
temp = *s;
*s = *(s + (--mark));
*(s + mark) = temp;
}
return;
}
i am having a string like
" X1 " ---> string lenght is 30
I have stored this to a chararry . ref
so here ref = " X1 "
now i trim the left space by my function . Si the string now becomes
"X1 " ---> string lenght is 15... (3 Replies)
If one wants to get a start address of a array or a string or a block of memory via a function, there are at least two methods to achieve it:
(1) one is to pass a pointer-to-pointer parameter, like:
int my_malloc(int size, char **pmem)
{
*pmem=(char *)malloc(size);
if(*pmem==NULL)... (11 Replies)
Hello everyone,
I'm writing a program using the id3lib unfortunately I've encountered with memory issue that cause segmentation fault. I tried to rerun and analyze the program with valgrind but it doesn't point me anywhere. I really stuck on this one.
Valgrind output:
==14716== Invalid read of... (2 Replies)
Hi,
Can any one tell me why my following program is crashing?
#include <iostream>
using namespace std;
class CA {
public:
const static int i;
};
const int CA::i = 10;
int main() {
int* pi = const_cast<int*>(&CA::i);
*pi = 9;
cout << CA::i << endl;
} (6 Replies)
I'm trying to write a programme which scans strings to find how many vowels they contain. I get an error saying that I'm trying to compare a pointer and an integer inif(*v == scanme){. How can I overcome this ? Also, the programme seems to scan only the first word of a string e.g.: if I type "abc... (1 Reply)
I'm newbie learner. My all friend use windows just only me use linux.
so i can't solve any problem by myself. i need a solution.
how can i use pointer as a string.
#include<string.h>
#include<stdio.h>
int main()
{
char *s='\0';
gets(s);
puts(s);
return 0;
}
This code work on... (6 Replies)
I am populating an array of string and print it.
But it going in infinite loop and causing segfault.
char Name = {
"yahoo",
"rediff",
"facebook",
NULL
};
main(int argc, char* argv)
{
int j = 0;
... (7 Replies)
I have a problem with scanf() for string pointer as member of a struct.
#include <stdio.h>
#include <stdlib.h>
struct Student {
int studentNumber;
int phoneNumber;
char *studentName; //line 7
// char studentName; //line 8
};
int... (10 Replies)
Hello, I am trying to reverse complement one string and reverse another (NO complement!), both with pointer. My code compiled without error, but did not do the job I wanted.
#include <stdio.h>
#include <stdlib.h>
#include <zlib.h>
#include "kseq.h"
// STEP 1: declare the type of file... (5 Replies)
Another project, another bump in the road and another chance to learn. I've been trying to open gzipped files and parse data from them and hit a snag. I have data in gzips with a place followed by an ip or ip range sort of like this:
Some place:x.x.x.x-x.x.x.x
I was able to modify some code... (6 Replies)
Discussion started by: Azrael
6 Replies
LEARN ABOUT NETBSD
strndup
STRDUP(3) BSD Library Functions Manual STRDUP(3)NAME
strdup, strndup -- save a copy of a string
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <string.h>
char *
strdup(const char *str);
char *
strndup(const char *str, size_t len);
DESCRIPTION
The strdup() function allocates sufficient memory for a copy of the string str, does the copy, and returns a pointer to it. The pointer may
subsequently be used as an argument to the function free(3).
If insufficient memory is available, NULL is returned.
The strndup() function copies at most len characters from the string str always NUL terminating the copied string.
EXAMPLES
The following will point p to an allocated area of memory containing the nul-terminated string "foobar":
char *p;
if ((p = strdup("foobar")) == NULL) {
fprintf(stderr, "Out of memory.
");
exit(1);
}
ERRORS
The strdup() function may fail and set the external variable errno for any of the errors specified for the library function malloc(3).
SEE ALSO free(3), malloc(3), strcpy(3), strlen(3)STANDARDS
The strdup() function conforms to IEEE Std 1003.1-2001 (``POSIX.1'').
HISTORY
The strdup() function first appeared in 4.4BSD. The strndup() function was added in NetBSD 4.0.
BSD January 28, 2009 BSD
09-16-2011
and the other code executes comfortably though both code uses same pointer arithmetic.