C/C++ :: Strtok And Null Checking?
Mar 1, 2015
I'm playing around with parts of code and am coming across some errors. Most of my concern is related to strtok(). I've used it before but with a char* named token. I used a while loop to continuously check whether token was equal to NULL. In the following code, however, there aren't any checks. I was wondering if that is why this code prints (null) while running. Also, I would like to know if it is possible to read input like this code attempts to do - assigning tokens to each variable one after the other.
The format of the input:
Zucchini, Squash, pound
Yellow, Squash, pound
Tomatoes, Ugly Ripe, each
#include <stdio.h>
#include <stdlib.h>
[code]....
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Jul 23, 2013
I am beginner in C++ programming. And i was try use STRTOK code with NULL fields, but in ARRAY fields NULL values is skiped. For example:
input text in Memo2:
AnsiString PAT02[100][20];
for (int IndexVRadku02 = 0; IndexVRadku02 < Memo2->Lines->Count ; IndexVRadku02++) {
AnsiString PNF02 = Memo2->Lines->Strings[IndexVRadku02];
char * PN02;
[Code] ....
Result:
Array 00 01 02 03 04 05
00 0000 TEXT1 TEXT2
01 0002 TEXT3 TEXT4 TEXT5
02 0003 TEXT6
But i need this result:
Array 00 01 02 03 04 05
00 0000 TEXT1 TEXT2
01 0002 TEXT3 TEXT4 TEXT5
02 0003 TEXT6
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Feb 18, 2014
I am looking at one of the functions of an exercise:
void escape(char * s, char * t) {
int i, j;
i = j = 0;
while ( t[i] ) {
/* Translate the special character, if we have one */
switch( t[i] ) {
[code]...
Notice the while loop evaluates the current value in t to true or false. When we hit the null terminator, does that get evaluated as 0 and hence evaluates as a falsy value so the while loop exits?
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Mar 31, 2015
When you login to my site my loginservice which is done by ajax and json make a session called context.Session["Name"]. With BreakPoints it shows that everything is good and the variables are in place. However when I use Session["Name"] it comes out as null.
I will add my code at the bottem not
using System;
using System.Collections.Generic;
using System.Linq;
[Code].....
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Nov 28, 2013
Assuming that we have the string :
Code:
***HELLO&SIR. & and * is the delimiters.
My question is how strtok will work in the beginning?
According to this to determine the beginning and the end of a token, the function first scans from the starting location for the first character not contained in delimiters (which becomes the beginning of the token). And then scans starting from this beginning of the token for the first character contained in delimiters, which becomes the end of the token. The scan also stops if the terminating null character is found.
This end of the token is automatically replaced by a null-character, and the beginning of the token is returned by the function. strtok will replace the first * with '' and the next call will start from the second * puts '' there and again the same with the third * ?
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Sep 27, 2014
How to use strtok and strcpy in a file?
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Nov 20, 2013
I wrote this program, it's supposed to take a user-specified file, which has a bunch of numbers, and add all the numbers in a line and give me a sum and average.
Sample file:
------------------------------------
2 1 2
3 1 2 3
4 1 2 3 4
------------------------------------
This would output:
------------------------------------
Group Size = 2
i = 1 number = 1 Sum = 1
i = 2 number = 2 Sum = 3
Average = 1.50
Group Size = 3
i = 1 number = 1 Sum = 1
i = 2 number = 2 Sum = 3
i = 3 number = 3 Sum = 6
Average = 2.00
Group Size = 4
i = 1 number = 1 Sum = 1
i = 2 number = 2 Sum = 3
i = 3 number = 3 Sum = 6
i = 4 number = 4 Sum = 10
Average = 2.50------------------------------------
// END CONTEXT
Anyway, I wrote this program. Here it is. But strtok doesn't want to advance to teh next token?
Code:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main(void){
int a, sum, number, groupsize;
}
[code].....
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Sep 18, 2013
I am having a problem with the output of a file. My function does everything it needs to do with the exception of one line. I have a .dat file with the following:
Code:
joe clint james brint howard
jimmy
alexander
*
me
When I run the function my output is as such:
Code:
file opened
word: joe
digit: 3
word: clint
digit: 5
word: james
[Code] .....
ERROR non alphanumeric digit on line 4!
File closed "Howard" is only six digits in length. Also it seems to skips a line in the output which could be the extra character but I am not sure. What I find very interesting is the other names, (jimmy & alexander) on separate lines do not have that problem.
Here is my function:
Code:
#include "main.h"
#include "fileCheck.h"
int fileCheck(FILE *fp){
int line_count = 0;
int ret_val = 0;
int digit_count = 0;
char file[BUFF];
[Code] .....
How I can correct this? I am aware of sscanf to parse the line but I do not know the format of the file. All I know is the file will be alphanumeric and if there is a non-alphanumeric, I must print out an error with the line it occurred on such as the above output.
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Jul 14, 2014
I am trying to make simpler equivalent of strtok().i want to separate string for my command line program. here is what i came up with
Code:
PVOID CmdArgs(PWCHAR Arg){
PWCHAR Return[10];
int I=0,s=0;
}
[code]....
i can not use winapi or standard c library because project im doing is pure ntdll api program (subsystem native in other words)
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Oct 31, 2012
I have a string like "THIS::IS::THE:EXAMPLE::STRING"
I want to split the string to tokens based on "::".
The tokens should be:
THIS
IS
THE:EXAMPLE
EXAMPLE
STRING
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Feb 28, 2014
I had an assignment to do a palindrome program but im stuck in this part.
"This c-string will be sent to a function that will remove all spaces and punctuation marks from its c-string as well as change any uppercase letters to lowercase. Use string tokens to eliminate the spaces & punctuation marks. Make sure you include the NULL as you concatenate the tokens into a c-string. Then copy back into the original c-string for the pass by reference."
void tokenptr(char drome[]) {
char *token;
size_t i;
token = strtok(drome, " ,.!:;?");
while (token != ' ') {
[Code] .....
I'm pretty sure I did that part except how can i pass this cstring back to main? We really haven't even touched much of pointers except to use strtok().
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May 2, 2013
I'm trying to read a file from the 2nd argument, skipping the first line of the file since it's the name of the columns, and separate each line as a token, by date, subject, startTime, endTime, and location.Here's my code that I got so far:
Code:
void readAppointment(){
if (arg != 2)
exit;
else {
FILE *fp;
fp = fopen( argv[1], "r");
char line[999];
[code]....
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Feb 17, 2013
In the assignment we are forbidden to use fscanf(). I have been trying to get this to work, but I've started to realize that I do not have a complete understanding of what strtok() actually does. I'm getting this warning when debugging: "assignment makes integer from pointer without cast."
This warning happens when assigning str to goal and assist, and I think it is because they are, when dereferenced, integers. The code below correctly assigns the name into the correct spot, but leaves nonsense data in the goal and assist arrays.
ex:-7880, -7888 file example: NAME GOALS ASSISTS JOHN 1 2
Code:
void readLinesFromFile( FILE* Ptr, int* goal, int* assist, char** name, int lines ){/*
* Reads lines from files and populates the arrays with the corresponding info.
*/
int index;
char hold[ MAX_LINE ] = { 0 };
char* str = NULL;
[Code] .....
From what I understand about strtok(), it returns a string, and takes in a character array and a key value that tells it when to stop. In the online examples I've seen, they use NULL in the first field. I'm not sure why.
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Sep 19, 2013
I usually check if a bit is set using:
Code: bit = (number >> n) & 1; where `n` is the bit I want to check...
But I came across a stackoverflow answer saying:
bit = number & (1 << x); will not put the value of bit x into bit unless bit has type _Bool (<stdbool.h>).
Otherwise, bit = !!(number & (1 << x)); will..
So why is this? why the double !?
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Nov 4, 2013
Everything seems to be correct from my perspective. heres the program: Code: /*c program to check whether a string is palindrome or not*/
#include<stdio.h>
#include<string.h>
int main(void) {
char str[30];
int i,j,flag=0;
[Code] .....
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Dec 8, 2013
The reason being is that it says that my program is right
Code:
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#define NFlights 10
struct date {
int month;
int day;
int year;
int hour;
int minute;
[Code] ....
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Jun 15, 2013
Q. In context of C language syntax checking, which of the following can be modeled using Finite Automata?
(A) Detecting proper termination of an instruction.
(B) Detecting balance of parentheses.
(C) Detecting initialization of a variable.
(D) None of the above.
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Jan 31, 2015
I am new to C++ , i want to know how to check if a key with modifier is pressed.
When I use GetAsyncKeyState() it gives me error identifier not found.
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Aug 4, 2013
I think I may have found a new way of checking for 3d polygon collisions, but I'm not sure. The method involves...
1. finding the planes that the primitives lie on
2. finding the line where the planes intersect
3. if both polys have points on both sides of the line AND have points that overlap on the 1d space of the line, then they intersect.
I have some half done code testing this, and so far it seems to be sound and fairly fast. These are some average time-tests done on my machine for each part:
1. 30 microseconds (both)
2. 7 microseconds
3. TBD
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Jun 17, 2014
I have a question, how can I check if a program is running using c++? For example
if (notepad.exe is running) {
.... ..... ....
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Jul 20, 2014
How would I go about checking for deallocated memory?
For example, let's take this into consideration:
// Unsigned 32-bit / 64-bit integer: uint32, uint64
uint32* Pointer = new uint32[ Size ];
uint64 MemAddr = ( uint64 ) Pointer;
delete[] Pointer;
The above code would proceed to create a new array, store it in a pointer and retrieve the memory address of the array before finally deleting the array.
So let's assume we re-build the pointer and try to access the now deallocated array:
Pointer = ( uint32* ) MemAddr;
Pointer[ 0 ] = 0;
Based on the above snippets of code, how would I check "Pointer" after rebuilding the memory to check if the rebuilt memory has actually been deallocated. Without a check we'd get an exception error.
A bit of detail on why I am trying this:
Before thinking up how to do this, I was storing the addresses in a list and check the list for the addresses to see if they existed or not. However this requires an O(n) search, which isn't exactly what I am wanting. So instead if I used a check for deallocation method, I can go for an O(1) time check and reduce the total time it would take to check for memory allocation/deallocation.
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Jan 23, 2014
I have created a prompt which prompts the user for an integer and I have set up a loop to check for if it is an integer or not. My "bug" is that a user can enter an "integer" and "space" and "enter" and it does not give any error and assumes that "All is FINE!". I have gotten the value from the ascii table of 'SPACE' and put it as a check in my parameter of while, but it does not work.
Here is my code:
int x, y, boolean, i;
char buff[256];
printf("Enter the first integer value: ");
scanf("%s", buff);
i = 0;
boolean = 0; //initializing our boolean var that will eventually decide if we have an error or not
[code]....
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Mar 6, 2014
Suppose you have a templated class, such as
template <typename T>
class Matrix {
// some stuff and some methods
};
and let's say that you have some methods that need to do some type-dependent stuff, like, for example,
template <typename T>
Matrix<T> Matrix<T>::transpose() const {
// get this->rowCount, this->columnCount
// create a Matrix that has rowCount amount of columns and columnCount amount of rows
// copy (*this)[j][k] to theMatrix[k][j] (for all of the entries in *this)
// if the entries are complex, take the complex conjugate of them all
}
Would it be good practice to check explicitly for the typename parameter (or is this, somehow, defeating the purpose of templates)? std::cout << "I know that this is a design question, but it needs to be asked... ";
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Oct 13, 2013
Assuming I have a list of pointers to a generic type T:
#include <vector>
//...
list<T*> myList;
Now assuming I want to go on the list, and if T's type is matched to the type I'm looking for, then cast it to this type and do something. List shown here:
list<T*>:: const_iterator iter= myList.begin();
for(; iter!=myList.end(); ++iter){
if( typeid(*iter)==typeid(Something*)) //RUN-TIME ERROR
dynamic_cast<Something*>(*iter)->DoSomething();
}
how do I fix this run-time error?
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Feb 14, 2014
#include <iostream>
using namespace std;
int main(){
int x;
cout << "Enter character:";
cin >> x;
[Code] ....
If i type in:
+
How come it says that "this is not addition?
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Jun 5, 2013
I have this table Profile which has fields with user_Id and regNo and I want to check first if id and email are already exists before proceed to inserting datas. In my codes, I am able to validate only one row (either id or reg number), but if I am going to validate the two of them, it gives me an error, saying "Must declare the scalar variable @userid". I dont know if it is with my select that is wrong or something in my codes
SqlConnection con = new SqlConnection("Data Source=GATE-PCSQLEXPRESS;Initial Catalog=dbProfile;Integrated Security=True");
con.Open();
SqlCommand cmdd = new SqlCommand("select * from Profile where user_Id = @userid AND RegNo = @reg", con);
SqlParameter param = new SqlParameter();
[Code] .....
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