This is what I came up with, but I always get a Run-Time Check Failure #2 - Stack around the variable 'h' was corrupted.
int mostCommonLetter(char s[]) {
int i=0, h[26],k=0, max=0, number=0;
while ( k < 26){
h[k] = '0';
k++;
}
while(s[i] != '\0'){
h[whichLetter(s[i])] = h[whichLetter(s[i])]+1;
i++;
}
h[26] = '\0';
for(i=0;h[i]!='\0';i++){
if(h[i] > max)
number=i;
}
return number;
}
You cannot do h[26] = '\0'; - h has 26 elements indexed 0..25. As you know the length of h you don't need to 0-terminate it, simply do for (i=0; i < 26; ++i)
Also, are you certain whichLetter always returns a value in the 0..25 range? What does it do if it e.g. encounters a space?
This writes past the end of the array:
h[26] = '\0';
Make the for loop depend on the length rather than the last character:
for(i=0;i<26;i++){
if(h[i] > max)
number=i;
}
Related
I'm a beginner programmer that is learning C and I'm doing some exercises on LeetCode but I ran with a problem with today's problem, I'm going to put the problem bellow but my difficult is on a do while loop that I did to loop the deleting function if there are adjacent duplicates, my code can delete the duplicates on the first iteration, but it's not looping to do any subsequent tasks, if anyone could help my I would be grateful.
The LeetCode Daily Problem (10/11/2022):
You are given a string s consisting of lowercase English letters. A duplicate removal consists of choosing two adjacent and equal letters and removing them.
We repeatedly make duplicate removals on s until we no longer can.
Return the final string after all such duplicate removals have been made. It can be proven that the answer is unique.
Example 1:
Input: s = "abbaca"
Output: "ca"
Explanation:
For example, in "abbaca" we could remove "bb" since the letters are adjacent and equal, and this is the only possible move. The result of this move is that the string is "aaca", of which only "aa" is possible, so the final string is "ca".
Example 2:
Input: s = "azxxzy"
Output: "ay"
Constraints:
1 <= s.length <= 105
s consists of lowercase English letters.
My code (testcase: "abbaca"):
char res[100]; //awnser
char * removeDuplicates(char * s){
//int that verifies if any char from the string can be deleted
int ver = 0;
//do while loop that reiterates to eliminate the duplicates
do {
int lenght = strlen(s);
int j = 0;
int ver = 0;
//for loop that if there are duplicates adds one to ver and deletes the duplicate
for (int i = 0; i < lenght ; i++){
if (s[i] == s[i + 1]){
i++;
j--;
ver++;
}
else {
res[j] = s[i];
}
j++;
}
//copying the res string into the s to redo the loop if necessary
strcpy(s,res);
} while (ver > 0);
return res;
}
The fuction returns "aaca".
I did some tweaking with the code and found that after the loop the ver variable always return to 0, but I don't know why.
I see two errors
res isn't terminated so the strcpy may fail
You have two definitions of int ver so the one being incremented is not the one being checked by while (ver > 0); In other words: The do-while only executes once.
Based on your code it can be fixed like:
char res[100]; //awnser
char * removeDuplicates(char * s){
//int that verifies if any char from the string can be deleted
int ver = 0;
//do while loop that reiterates to eliminate the duplicates
do {
int lenght = strlen(s);
int j = 0;
ver = 0; // <--------------- Changed
//for loop that if there are duplicates adds one to ver and deletes the duplicate
for (int i = 0; i < lenght ; i++){
if (s[i] == s[i + 1]){
i++;
j--;
ver++;
}
else {
res[j] = s[i];
}
j++;
}
res[j] = '\0'; // <---------------- Changed
//copying the res string into the s to redo the loop if necessary
strcpy(s,res);
} while (ver > 0);
return res;
}
Why I am getting a space character in my program in the place of third last character?
Even if I change the string str variable I get the same result.
#include <stdio.h>
#include <string.h>
void parser(char array[])
{
int a, b;
for (int i = 0; i < strlen(array); i++) {
if (array[i] == '>') {
a = i;
break;
}
}
for (int j = a; j < strlen(array); j++) {
if (array[j] == '<') {
b = j;
}
}
for (int p = 0, q = a + 1; p < b - a - 1, q < b; p++, q++) {
array[p] = array[q];
array[b - a] = '\0';
printf("%c", array[p]);
}
}
int main()
{
char str[] = "<h1>hello there i am programmer.</h1>";
parser(str);
return 0;
}
There are many things that could be written better in the code but they do not affect the result.
The line that produces the unexpected outcome is:
array[b-a]='\0';
When this for loop starts...
for(int p=0,q=a+1;p<b-a-1,q<b;p++,q++){
array[p]=array[q];
array[b-a]='\0';
printf("%c",array[p]);
}
... the values of a and b are 3 and 32.
The statement array[b-a]='\0'; puts the NUL terminator character at position 29 in array.
The loop starts with p=0, q=4 (a+1) and repeats until p reaches 28 and q reaches 31 (q<b)*.
When p is 25, q is 29 and array[29] has been repeatedly set to '\0' on the previous iterations, therefore '\0' is copied at position 25 and printed on screen.
You should set the NUL terminator only once, after the loop. And the right position for it is b-a-1, not b-a; you expressed this correctly in the for initialization (p=0) and exit condition (p<b-a-1).
All in all, the code around the last for loop should be like this:
for(int p=0, q=a+1;q<b;p++,q++){
array[p]=array[q];
printf("%c",array[p]);
}
array[b-a-1]='\0';
*The condition p<b-a-1 is ignore because of the comma character. You probably want & between the conditions but they are equivalent, one of them is enough.
I was doing a program to copy all string words other than its first 2 words and putting a x at the end of it.
However i cant put x at its end. Please help!!!!
Below is my code.
#include<stdio.h>
#include<string.h>
int main()
{
char a[25], b[25];
int i, j, count = 0, l, k;
scanf("%[^\n]s", a);
i = strlen(a);
if (i > 20)
printf("Given Sentence is too long.");
else
{/* checking for first 2 words and counting 2 spaces*/
for (j = 0; j < i; j++)
{
if (a[j] == ' ')
count = count + 1;
if (count == 2)
{
k = j;
break;
}
}
/* copying remaining string into new one*/
for (j = 0; j < i - k; j++)
{
b[j] = a[j + k];
}
b[j + 1] = 'x';
printf("%s", b);
}
}
you are removing first two index. But you wrote k=j and if you check the current value j there it's 1. so you are updating wrongly k because you removed 2 indexes. So k value should be 2. So checked the below code
/* copying remaining string into new one*/
for (j = 0; j < i - 2; j++)
{
b[j] = a[j + 2];
}
b[j + 1] = 'x';
printf("%s", b);
Your index is off by one. After your second loop, the condition j < i-k was false, so j now is i-k. Therefore, the character after the end of what you copied is b[j], not b[j+1]. The correct line would therefore be b[j] = 'x';.
Just changing this would leave you with something that is not a string. A string is defined as a sequence of char, ending with a '\0' char. So you have to add b[j+1] = 0; as well.
After these changes, your code does what you intended, but still has undefined behavior.
One problem is that your scanf() will happily overflow your buffer -- use a field width here: scanf("%24[^\n]", a);. And by the way, the s at the and doesn't make any sense, you use either the s conversion or the [] conversion.
A somewhat sensible implementation would use functions suited for the job, like e.g. this:
#include<stdio.h>
#include<string.h>
int main(void)
{
// memory is *cheap* nowadays, these buffers are still somewhat tiny:
char a[256];
char b[256];
// read a line
if (!fgets(a, 256, stdin)) return 1;
// and strip the newline character if present
a[strcspn(a, "\n")] = 0;
// find first space
char *space = strchr(a, ' ');
// find second space
if (space) space = strchr(space+1, ' ');
if (space)
{
// have two spaces, copy the rest
strcpy(b, space+1);
// and append 'x':
strcat(b, "x");
}
else
{
// empty string:
b[0] = 0;
}
printf("%s",b);
return 0;
}
For functions you don't know, google for man <function>.
In C strings are array of chars as you know and the way C knows it is end of the string is '\0' character. In your example you are missing at the last few lines
/* copying remaining string into new one*/
for(j=0;j<i-k;j++)
{
b[j]=a[j+k];
}
b[j+1]='x';
printf("%s",b);
after the loop ends j is already increased 1 before it quits the loop.
So if your string before x is "test", it is like
't', 'e', 's', 't','\0' in char array, and since your j is increased more than it should have, it gets to the point just right of '\0', but characters after '\0' doesnt matter, because it is the end, so your x will not be added. Simple change to
b[j]='x';
I'm writing a function that finds the most common alphabetic character in a file. The function should ignore all characters other than alphabetic.
At the moment I have the following:
int most_common(const char *filename)
{
char frequency[26];
int ch = 0;
FILE *fileHandle;
if((fileHandle = fopen(filename, "r")) == NULL){
return -1;
}
for (ch = 0; ch < 26; ch++)
frequency[ch] = 0;
while(1){
ch = fgetc(fileHandle);
if (ch == EOF) break;
if ('a' <= ch && ch <= 'z')
frequency[ch - 'a']++;
else if ('A' <= ch && ch <= 'Z')
frequency[ch - 'A']++;
}
int max = 0;
for (int i = 1; i < 26; ++i)
if (frequency[i] > frequency[max])
max = i;
return max;
}
Now the function returns how many times the most frequent letter occurred, not the character itself. I'm a bit lost, as I'm not sure if that's the way this function should look like at all. Does it make sense and how possibly can I fix the problem?
I would really appreciate your help.
The variable frequency is indexed by the character code. So frequency[0] is 5, if there have been 5 'a's.
In your code you are assigning the count to max, not the character code, so you're returning the count not the actual character.
You need to store both the maximum frequency count and the character code that it referred to.
I would fix this with:
int maxCount = 0;
int maxChar = 0;
// i = A to Z
for (int i = 0; i <= 26; ++i)
{
// if freq of this char is greater than the previous max freq
if (frequency[i] > maxCount)
{
// store the value of the max freq
maxCount = frequency[i];
// store the char that had the max freq
maxChar = i;
}
}
// character codes are zero-based alphabet.
// Add ASCII value of 'A' to turn back into a char code.
return maxChar + 'A';
Note that I changed int i = 1 to int i = 0. Starting at 1 would mean starting at B, which is a subtle bug you might not notice. Also, the loop should terminate at <= 26, otherwise you'd miss out Z too.
Note the braces. Your braces style (no braces for single-statement blocks) comes very highly un-recommended.
Also, i++ is more common than ++i in cases like this. In this context it will make no difference, so would advise i++.
I have the following code that I use to normalize a char array. At the end of the process, the normalized file has some of the old output leftover at the end. This is do to i reaching the end of the array before j. This makes sense but how do I remove the extra characters? I am coming from java so I apologize if I'm making mistakes that seem simple. I have the following code:
/* The normalize procedure normalizes a character array of size len
according to the following rules:
1) turn all upper case letters into lower case ones
2) turn any white-space character into a space character and,
shrink any n>1 consecutive whitespace characters to exactly 1 whitespace
When the procedure returns, the character array buf contains the newly
normalized string and the return value is the new length of the normalized string.
hint: you may want to use C library function isupper, isspace, tolower
do "man isupper"
*/
int
normalize(unsigned char *buf, /* The character array contains the string to be normalized*/
int len /* the size of the original character array */)
{
/* use a for loop to cycle through each character and the built in c funstions to analyze it */
int i = 0;
int j = 0;
int k = len;
if(isspace(buf[0])){
i++;
k--;
}
if(isspace(buf[len-1])){
i++;
k--;
}
for(i;i < len;i++){
if(islower(buf[i])) {
buf[j]=buf[i];
j++;
}
if(isupper(buf[i])) {
buf[j]=tolower(buf[i]);
j++;
}
if(isspace(buf[i]) && !isspace(buf[j-1])) {
buf[j]=' ';
j++;
}
if(isspace(buf[i]) && isspace(buf[i+1])){
i++;
k--;
}
}
return k;
}
Here is some sample output:
halb mwqcnfuokuqhuhy ja mdqu nzskzkdkywqsfbs zwb lyvli HALB
MwQcnfuOKuQhuhy Ja mDQU nZSkZkDkYWqsfBS ZWb lyVLi
As you can see the end part is repeating. Both the new normalized data and old remaining un-normalized data is present in the result. How can I fix this?
add a null terminator
k[newLength]='\0';
return k;
to fix like this
int normalize(unsigned char *buf, int len) {
int i, j;
for(j=i=0 ;i < len; ++i){
if(isupper(buf[i])) {
buf[j++]=tolower(buf[i]);
continue ;
}
if(isspace(buf[i])){
if(!j || j && buf[j-1] != ' ')
buf[j++]=' ';
continue ;
}
buf[j++] = buf[i];
}
buf[j] = '\0';
return j;
}
or? add a null terminator
k[newLength] = NULL;
return k;