A string consisting of words, no longer than 100 characters, is supplied. Words consist of Latin characters and are separated by a single space. It is necessary to output to the standard output stream a string containing only the words palindromes.
The source data must be read into memory as a whole and all manipulations must be carried out in memory, the result obtained in memory and then printed.
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int check(char str[])
{
int i, length;
length = strlen(str);
for (i = 0; i < length; i++)
if (str[i] != str[(length - 1) - i]) return 0;
return 1;
}
int main(void)
{
char str[100];
char* t;
gets(str);
t = strtok(str, " ");
while (t != NULL) {
if (check(t) == 1) {
printf("%s ", t);
}
t = strtok(NULL, " ");
}
_getch();
return 0;
}
this is my code (it fails the tests)
Please help me fix the code
Instead of fgets use function getline(&buffer, &size, stdion) for example.
Your for loop in the check function works fine but resolve another problem, than that you expected.
Palindrome a word or group of words that is the same when you read it forwards from the beginning or backwards from the end.
Related
So im trying to get a binary number from using the strtok function to iterate through a user inputted string. If the user inputs alpha it prints a 0 and if the user inputs beta it will output a 1.So if a user types in "alpha beta alpha beta alpha" the output should be "01010". I have the following code but im not sure where im going wrong as it is not doing the behavior i described
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
int main(int argc, char * argv[])
{
char userinput[250];
long binaryarray[250];
char *token;
int counter = 0;
long binarynumber = 0 ;
printf("enter alpha or beta");
scanf("%s", userinput);
token = strtok(userinput, " ");
while (token != NULL)
{
if(!strcmp(token, "alpha"))
{
binaryarray[counter] = 0;
counter += 1;
}
if(!strcmp(token, "beta"))
{
binaryarray[counter] = 1;
counter += 1;
}
token = strtok(NULL, " \0");
}
for(int i = 0; i < counter; i++)
{
binarynumber = 10 * binarynumber + binaryarray[i];
}
printf("%ld", binarynumber);
}
How would I fix this issue?
The problem is, for
scanf("%s",userinput);
the scanning stops after encountering the first whitespace. So, it cannot scan and store an input like
alpha beta alpha beta alpha
separated by whitespace. Quoting C11, chapter ยง7.21.6.2
s
Matches a sequence of non-white-space characters.
Possible Solution: You need to use fgets() to read the user input with whitespaces.
As already said by #SouravGhosh you should use fgets to store the whole string inserted by user with white spaces.
#include <stdio.h>
#include <string.h>
int main(int argc, char * argv[])
{
char userinput[250] = {0};
char binaryarray[250];
char* token;
size_t counter = 0;
printf("enter alpha or beta");
fgets(userinput, sizeof(userinput), stdin);
token = strtok(userinput, " \n\0");
while (( token != NULL) && (count < sizeof(binaryarray)))
{
if(!strcmp(token,"alpha"))
{
binaryarray[counter] = '0';
counter++;
}
else if(!strcmp(token,"beta"))
{
binaryarray[counter] = '1';
counter++;
}
token = strtok(NULL, " \n\0");
}
for(size_t i=0 ; i< counter; i++)
{
printf("%c", binaryarray[i]);
}
printf("\n");
}
But you have other problems:
Your tokens should be " \n\0" to match all possible chars between words.
All tokens must be checked with the first strok in case of a single input, so no whitespaces
Using an int to calculate your "binary" and print it with "%ld" format specifier does not print leading zeros. You can directly store chars into the buffer.
This code don't count words properly. I don't know if it is wrong on the for or what. Need help.
#include <stdio.h>
#include <stdlib.h>
int count_p(char sentence[100]) {
int i, m = 1;
for (i = 0 ; i < 100 ; i++) {
if (sentence[i] == ' ') {
m += 1;
}
}
return(m);
}
void main() {
char s[100];
int p;
printf("Sentence here: ");
scanf("%s", &s[50]);
p = count_p(sentence);
printf("Words: %d", p);
printf("\n");
}
The %s in scanf stops reading when it found a whitespace. Therefore, ' ' won't appear in s unless it was there as indeterminate value in uninitialized variable.
You can use fgets to read a whole line.
Here is a fixed code that also checks for end of the string.
#include <stdio.h>
#include <stdlib.h>
int count_p(char sentence[100]) {
int i, m = 1;
for (i = 0 ; i < 100 && sentence[i] != '\0'; i++) {
if (sentence[i] == ' ') {
m += 1;
}
}
return(m);
}
int main(void) {
char s[100];
int p;
printf("Sentence here: ");
fgets(s, sizeof(s), stdin);
p = count_p(s);
printf("Words: %d", p);
printf("\n");
return 0;
}
scanf("%s", &s[50]);
Not a correct way to take input and writing at index which is out of bound. Do this instead -
scanf("%99[^\n]", s); // this will read 99 characters and until '\n' is encountered
In main you function call is incorrect -
p = count_p(sentence); // sentence is not declares in main
Call like this -
p = count_p(s); // pass s instead of sentence to function
Also in function count_p change ccondition in for loop as -
size_t i;
size_t len=strlen(s);
for (i = 0 ; i < len ; i++)
You see &s[50] means that you pass a pointer to the 51-th element of s, you then try to access s from the beginning but, the first 50 characters in s were not yet initialized, this leads to undefined behavior.
Also, your loop from 0 to 99 will have the same issue since you might input a string of less than 100 characters, in that case you would be accessing uninitialized data too.
You can fix your program by changing this
scanf("%s", &s[50]);
to
scanf("%99s", s);
and then
for (i = 0 ; i < 100 ; i++) {
to
for (i = 0 ; s[i] != '\0' ; i++) {
because scanf() will append a '\0' to make the array a valid c string, that's also the reason for the "%99s".
Another problem is that, if you want white space characters not to make scanf() stop reading, you need a different specifier, because "%s" stops at the first white space character, this is a suggestion
scanf("%99[^\n]", s);
Or you can do as #MikeCAT suggested and go with fgets(). But be careful with the trailing '\n' in case of fgets().
And finally, altough highly unlikely in this situation, scanf() might fail. To indicate success it returns the number of specifiers actually matched, thus it might indicate partial success too. It's fairly common to see the return value of scanf() ignored, and it's very bad when you have a "%d" specifier for example because then the correspoinding parameter might be accessed before initializing it.
The statement scanf("%s", &s[50]); is in correct in your situation.Since you want to enter a sentence separated by spaces,the correct way of doing it is :
scanf(" %99[^\n]s",sentence);
That will prevent buffer overflow and allow space between words.Also your program does not seem to count words correctly if the sentence has consecutive whitespaces.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int count_p(char *sentence);
void main()
{
char sentence[100];
printf("Sentence here: ");
scanf(" %99[^\n]s",sentence);
int p = count_p(sentence);
printf("Words: %d", p);
printf("\n");
}
int count_p(char *sentence)
{
int len = strlen(sentence);
int x = 0 , wordCount = 0;
for( int n = 0 ; n < len ; n++ )
{
x++;
if( sentence[n] == ' ' )
x = 0;
if( x == 1 )
wordCount++;
}
return wordCount;
}
I am trying to write a simple C program to output the length of words and output their frequencies. For example, if the user inputs "hey" my program would output Length of word: 3 Occurrences 1, and so on with a larger string inputted. I just cannot seem to loop it properly. I thought of setting both counters when a delimiter is seen to count both the length of the word at the time and its occurrence but I have not found a way for it to work. How can I fix my loop? My code is below. I'd appreciate any help. I should include my program only runs correctly for one word inputted but not a whole sentence or multiple sentences.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
const char delim[] = ", . - !*()&^%$##<> ? []{}\\ / \"";
const int n_delim = 31;
#define SIZE 1000
int is_delim(int c);
int main(){
char string[SIZE];
int wordlength = 0, wl[SIZE];
int word = 0, i;
printf("Enter your input string:");
fgets(string, SIZE, stdin);
string[strlen(string) - 1] = '\0';
printf("Word Length\tCount\n");
int seen = 0;
int l;
for (i = 0; i < strlen(string); i++){
if (is_delim(string[i])){
wl[word++] = wordlength;
l = wordlength;
seen++;
printf("%d\t\t%d\n", l, seen);
wordlength = 0;
}
wordlength++;
}
return 0;
}
int is_delim(int c){
register int i;
for (i = 0; i < n_delim; i++)
if (c == delim[i]) return 1;
return 0;
}
The trick is that wl[n] holds the count of words
of length n. Also, you don't need to keep calling strlen()
on every iteration, just check for the zero byte at the end.
The optimizer will do this for you, if you enable it.
The odd-looking for(;1;) is so that the loop counts
the final word, which is terminated by the zero byte.
memset(wl,0,sizeof(wl));
for(wordStart=maxLength=i=0;1;i++) {
if(is_delim(string[i]) || string[i]==0) {
int wordLength= i-wordStart;
if(wordLength>0)
wl[wordLength]++;
if(wordLength>maxLength)
maxLength= wordLength;
wordStart= i+1;
}
if(string[i]==0)
break;
}
for(i=1;i<=maxLength;i++) {
if(wl[i]>0) {
printf("%d words of length %d.\n",wl[i],i);
}
}
You really should use strtok for this. Right now, you never compare the last string with the current one so you can't tell them apart. You can use strcmp for this. Finally instead of manually testing the length of the string you should use strlen. Here is how your loop could look like
int seen = 0;
pch = strtok(string, delim);
last = pch;
while(pch != NULL) {
if(strcmp(last, pch) != 0) {
printf("%s:\t%d\t\t%d\n", last, (int)strlen(last), seen);
seen = 1;
}else {
seen++;
}
last = pch;
pch = strtok(NULL, delim);
}
printf("%s:\t%d\t\t%d\n", last, (int)strlen(last), seen);
Note, you should set the variable seen to 0 before the loop.
Hi I am still new to c and have been working on this word sort program for some time now. the guidelines are:
Write a program that sorts a series of words entered by the user. Assume that each word is no more than 20 characters long. Stop reading when the user enters an empty word. Store each word in a dynamically allocated string, using an array of pointers (use the read_line function). After all lines have been read sort the array. Then use a loop to print the words in sorted order.
The problem I seem to be having is that the program will accept words but when I enter the empty word it goes to a new line and nothing happens. An help or advice would be greatly appreciated. here is my code so far.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define LEN 20
#define LIM 20
int read_line(char str[], int n);
void sort_str(char *list[], int n);
int alpha_first(char *list[], int min_sub, int max_sub);
int main(void)
{
char *list[LIM];
char *alpha[LIM];
char word_str[LEN];
int word, i, j, num_count = 0;
for(;;){
printf("Enter a word: ");
scanf("%s", &word);
if(word == NULL)
break;
else
read_line(word_str, LEN);
list[i] = malloc(strlen(word_str) + 1);
strcpy(list[i], word_str);
alpha[i] = list[i];
}
sort_str(alpha, i);
for(i = 0; i < num_count; ++i){
printf("Sorted: ");
puts(list[i]);
}
return (0);
}
int read_line(char str[], int n)
{
int ch, i = 0;
while ((ch = getchar()) != '\n')
if (i < n)
str[i++] = ch;
str[i] = '\0';
return i;
}
void sort_str(char *list[], int n)
{
int i, index_of_min;
char *temp;
for (i= 0; i < n - 1; ++i) {
index_of_min = alpha_first(list, i, n - 1);
if (index_of_min != i) {
temp = list[index_of_min];
list[index_of_min] = list[i];
list[i] = temp;
}
}
}
int alpha_first(char *list[], int min_sub, int max_sub){
int i, first;
first = min_sub;
for(i = min_sub + 1; i <= max_sub; ++i){
if(strcmp(list[i], list[first]) < 0){
first = i;
}
}
return (first);
}
Your logic flow is flawed. If a word is entered, the scanf() will eat it from stdin and store a null-terminated string at the address of the integer 'word'. Any more than 3/7 chars entered, (32/64 bit, allowing for the null terminator), will start corrupting the stack. read_line() will then only have the line terminator to read from stdin, (assuming the UB doesn't blow it up first).
The problem I seem to be having is that the program will accept words but when I enter the empty word it goes to a new line and nothing happens.
There are several problems with this:
char word_str[LEN];
int word, i, j, num_count = 0;
/* ... */
scanf("%s", &word);
if(word == NULL)
break;
First, scanf("%s", &word) scans whitespace-delimited strings, and to that end it skips leading whitespace, including newlines. You cannot read an "empty word" that way, though you can fail to read a word at all if the end of the input is reached (or an I/O error occurs) before any non-whitespace characters are scanned.
Second, you are passing an inappropriate pointer to scanf(). You should pass a pointer to a character array, but you instead pass a pointer to an int. It looks like maybe you wanted to scan into word_str instead of into word.
Third, your scanf() format does not protect against buffer overflow. You should provide a field width to limit how many characters can be scanned. Moreover, you need to be sure to leave room for a string terminator.
Fourth, you do not check the return value of scanf(). If it fails to match any characters to the field, then it will not store any. Since it returns the number of fields that were successfully scanned (or an error indicator), you can detect this condition.
One way to correct the scanf() and "empty word" test would be:
int result;
result = scanf("%*[ \t]%19[^ \t\n]", word_str);
if (result < 1) break;
(That assumes a fixed maximum word length of 19 to go with your declared array length of 20.) You have several additional problems in your larger code, large among them that read_line() attempts to read the same data you just read via scanf() (in fact, that function looks altogether pointless). Also, you never update num_count, and after calling sort_str() you lose track of the number of strings you've read by assigning a new value to variable i.
There may be other problems, too.
So after a few years of inactivity after studying at uni, I'm trying to build up my c experience with a simple string reverser.
here is my code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
*
*/
int main(int argc, char** argv) {
reverser();
return(0);
}
int reverser(){
printf("Please enter a String: ");
//return (0);
int len;
char input[10];
scanf("%s",&input);
int quit = strcmp(input,"quit");
if(quit == 0){
printf("%s\n","Program quitting");
return(0);
}
len = strlen(input);
printf("%i\n",len);
char reversed[len];
int count = 0;
while (count <= (len-1)){
//printf("%i\n",(len-count));
reversed[count] = input[(len-1)-count];
count++;
}
//printf("%s\n",input);
printf(reversed);
printf("\n");
reverser();
}
When I input "hello", you would expect "olleh" as the response, but I get "olleh:$a ca&#",
How do I just get the string input reversed and returned?
Bombalur
Add a '\0' at the end of the array. (as in, copy only chars until you reach '\0' - which is the point at array[strlen(array)], then when you're done, add a '\0' at the next character)
Strings are conventionally terminated by a zero byte. So it should be
char reversed[len+1];
And you should clear the last byte
reversed[len] = (char)0;
you forgot the \0 at the end of the string
This is because you are creating an array with size 10. When you take in some data into it (using scanf) and the array is not filled up completely, the printf from this array will give junk values in the memory. You should iterate for the length of the input by checking \n.
must have a size + 1 to string length so that you can have a \0 at the end of string that will solve your problem
The following is a (simple and minimal implementation of) string reverse program (obviously, error conditions, corner cases, blank spaces, wider character sets, etc has not been considered).
#include <stdio.h>
int strlen(char *s)
{
char *p = s;
while (*p)
p++;
return p - s;
}
char * strrev(char a[])
{
int i, j;
char temp;
for (i=0, j=strlen(a)-1 ; i<j ; i++, j--) {
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
return a;
}
int main()
{
char str[100];
printf("Enter string: ");
scanf("%s", str);
printf("The reverse is %s \n", strrev(str));
return 0;
}
Hope this helps!