I have been trying to make it so that placeholders like (%c) or (%d) are used as delimiters but whenever I try to it will also use the letter after the percent as a delimiter as well. Is there a way to make it so that both characters together are the delimiter and not so they are separate delimiters.
#include <stdio.h>
#include <string.h>
int main (void){
char string[100];
printf("Enter a string: ");
fgets(string,sizeof(string),stdin);
string[strlen(string)-1] = '\0';
char seperator[] = " %c";
char *token = strtok(string,seperator);
while(token != NULL){
printf("%s\n",token);
token = strtok(NULL,seperator);
}
return 0;
}
Related
I'm inputting the string str and want to print all of its words that contain the inputted character c on the position n (so if n = 1, it's the first character). I'm trying to do this using strtok() but I'm getting a weird crash. Any tips?
int main()
{
char str[100]; gets(str);
while(getchar()!='\n'); ///so that n or c don't scan a newline in them
int n; scanf("%d",&n);
char c; scanf("%c",&c);
char* token = strtok(str, " ");
while (token != NULL) {
if(token[n-1]==c){
printf("%s\n", token);
}
token = strtok(NULL, " ");
}
return 0;
}
I inputted the following:
Hi i like mint
2
i
Then the program suddenly crashes with the message:
Problem.exe has stopped working...
That while loop didn't seem necessary. Also, instead of gets(), I used fgets(). I moved most of the declarations at the beginning of function. This code now works probably.
#include <stdio.h>
#include <string.h>
int main()
{
int n;
char c, str[100];
fgets(str, 100, stdin);
scanf("%d %c",&n, &c);
char* token = strtok(str, " ");
while (token != NULL) {
if(token[n-1] == c) {
printf("%s\n", token);
}
token = strtok(NULL, " ");
}
return 0;
}
Here is the link where I tested it: https://ideone.com/KQkRrG
The task is: to read the text from file and to read an array of delimiters from keyboard. Than the program should search the sequence of delimiters in the text and, if it would be found 3 times or more, swap all the odd strings in a circle. Also it should detete all the words, which exceed the length limit, entered by user, but only in odd strings.
This is what i've got now:
#include "stdafx.h"
#include <stdio.h>
#include <conio.h>
int main(void)
{
setlocale(LC_ALL, "Russian"); //entering the text
const int numberOfCharactersToRead = 128;
char* inputText = (char*)(malloc(sizeof(char) * numberOfCharactersToRead));
FILE *fp;
fopen_s(&fp, "D:\texxxt.txt", "r");
if (fp == NULL)
{
printf("nFile not foundn");
system("pause");
return 0;
}
fgets(inputText, numberOfCharactersToRead, fp);
printf("Enter the sequence of delimiters: "); //entering delimiters
const int numberOfDelimitersToRead = 6;
char* delimiters = (char*)(malloc(sizeof(char) * numberOfDelimitersToRead));
int indexer = 0;
for (indexer = 0; indexer < numberOfDelimitersToRead; indexer++)
{
delimiters[indexer] = getchar();
}
//Trying to use strtok in order to devide text into rows (unsuccesful)
char delims[] = "/n";
char *pch = strtok_s(NULL, inputText, &delims);
printf("nLexems:");
while (pch != NULL)
{
printf("n%s", pch);
pch = strtok_s(NULL, inputText, &delims);
}
return 0;
}
int symcount(void)
{ //function searching the quantity of delimiters
char str[20], ch;
int count = 0, i;
printf("nEnter a string : ");
scanf_s("%s", &str);
printf("nEnter the character to be searched : ");
scanf_s("%c", &ch);
for (i = 0; str[i] != ''; i++)
{
if (str[i] == ch)
count++;
}
if (count == 0)
printf("nCharacter '%c'is not present", ch);
else
printf("nOccurence of character '%c' : %d", ch, count);
return (0);
}
I dont really know how to devide the text into rows and how to make my program differentiate even and odd strings. I'm really confused
The definition of strtok_s is the following:
char *strtok_s(char *strToken, const char *strDelimit, char **context);
You are mixing up the parameters. The 1st parameter should be a pointer to the input string and the 2nd parameter should be the delimiter string. Finally after the function is executed the 3rd parameter will be passed a pointer to the string after the position where the delimiter was found, or NULL if no delimiter was found. This pointer can then be passed onto the next strtok_s call to continue the search.
char *pchNext;
char *pch = strtok_s(inputText, delimiters, &pchNext);
while (pch != NULL)
{
printf("\n%s", pch);
pch = strtok_s(NULL, delimiters, &pchNext); // The first parameter can be NULL here
}
Also, the textual representation of the newline character is \n, not /n or n.
I am trying to process a character string in order to change something in a file. I read from a file a character string which contains a command and an argument, separated by a space character. I separated this array in tokens.
Now I want to pass the second token, which is the argument to a function. My problem is that when I run my program, the screen freezes and nothing happens. Here is my separating way and the call to the function.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void create_file(char *argument)
{
//some code goes here
}
int main()
{
int i = -1;
char *token[5];
char command[20];
const char delim[1] = " ";
FILE *fin;
fin = fopen("mbr.op", "r");
while(fscanf(fin, "%[^\n]", command) == 1)
{
i = -1;
token[++i] = strtok(command, delim);
while(token[i] != NULL)
token[++i] = strtok(NULL, delim);
if(strcmp(token[0], "CREATE_FILE") == 0)
create_file(token[1]);
}
fclose(fin);
return 0;
}
You have a few errors, first command[20] is an uninitialised string and that will cause undefined behaviour. Second, you failed to check the first arg as well as the second, so I added a test where commented. Also, the strings are not long enough so I removed the length. Lastly I test for a NULL pointer passed to the function.
Edit code was added to the question to show that command[20] was initialised, but it is still too short to take the command and a reasonable file name (thanks to #ameyCU).
#include <stdio.h>
#include <string.h>
void create_file(char *argument)
{
if(argument == NULL)
printf("NULL pointer\n");
else
printf("Arg: %s\n", argument);
}
int main(void)
{
int i = -1;
char *token[5];
char command[] = "CREATE_FILE myfile.txt";
const char delim[] = " ";
token[++i] = strtok(command, delim);
while(token[i] != NULL)
token[++i] = strtok(NULL, delim);
if(token[0] != NULL && strcmp(token[0], "CREATE_FILE") == 0) // added test
create_file(token[1]);
return 0;
}
Program output
Arg: myfile.txt
The first error is present in array definition:
const char delim[1] = " ";
In C "" is a string - an array of characters delimited by '\0'. This means that what stands to the right of "=" is a string of two chars:
// ' ' + '\0'
//0x20 0x00
Therefore this should be an array of two chars:
const char delim[2] = " ";
or
const char delim[] = " ";
I have a char array:
char tmp[2048];
I want to cut of the first x words of tmp. I define a word as a sequence of characters that does not include whitespaces. I tried something like this (should cut of the first 3 words):
sscanf(tmp, "%*s %*s %*s %s", tmp);
My problem is, that '%s' stops at the first whitespace it finds. I want the new string to end at the end of the old string, not at the first whitespace.
I'm also open for other suggestions how to cut of the first x words of a string. I define a word as a sequence of characters that doesn't contain whitespaces.
Here's a rough implementation:
const char* TrimWords(const char* input, int nWords)
{
while (nWords)
{
if (!isspace(*input) && isspace(*(input + 1)))
{
nWords--;
}
input++;
}
return input;
}
TrimWords("One Two Three Four Five", 3);
// returns " Four Five" after the first 3 words are trimmed.
Detailed input validation and error checking is left to the OP.
This is just a good starting point.
use strncpy(tmp, n, tmp+m); where m and n are ints
char tmp[20] = "abcdef";
strncpy(tmp, tmp + 3, 2);
for exmaple: code above will result in decdef
You can use strtok to tokenize strings by whitespace. Something similar to this could do what you're trying to achieve:
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[])
{
// Number of words to trim
const int numWords = 2;
char tmp[1024];
char buffer[1024];
sprintf(tmp, "this is a\tsentence.");
strcpy(buffer, tmp);
char* token = strtok(buffer, " \t");
for (int i = 0; i < numWords && token; i++) {
token = strtok(NULL, " \t");
}
if (token) {
size_t len = 1024 - (token - buffer);
memmove(tmp, tmp + (token - buffer), len);
}
else {
memset(tmp, '\0', 1024);
}
// Prints "a sentence."
printf("%s", tmp);
return 0;
}
However, the use of strtok is tricky at best. I would suggest using an approach similar to that of abelenky's answer.
I'm trying to split a string at spaces and tabs.
char * token = strtok(input, " \t");
works only for spaces. What am I doing wrong?
Here is an example that illustrates that strtok() will work on tabs or spaces.
The key is to pass in NULL on the all but the first call to strtok().
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[])
{
char buffer[1024];
int rv = sprintf(buffer, "a string\ttokenize.");
char *token = strtok(buffer, " \t");
int i = 0;
printf("cnt token\n");
printf("==========\n");
while (token) {
printf("%2d %s\n", i++, token);
token = strtok(NULL, " \t");
}
return 0;
}
output from above program is as follows below.
cnt token
==========
0 a
1 string
2 tokenize.