Hi I am doing a Cracking the Coding I have coded up a solution, by reading the answer explained in plain english, however I do not understand one line of code.
The Question
Replace all white space with "%20", empty spaces have been added at the end of the text to accomodate for the new symbols
Input : "Mr John Smith ", 13
Output : Mr%20John%20Smith
My Solution
*static void replaceSpaces(char[] arr,int trueLength)
{
int spaces = 0;
int newLength = 0;
int length = 0;
for(int i = 0; i<trueLength; ++i)
{
if(arr[i] == ' ')
{
++spaces;
}
newLength = trueLength +spaces*2; // We already have one space, so we need to add 2 extra spaces to fit the %20 symbol
}
for(int i = trueLength-1; i>=0; i--)
{
if(arr[i] == ' ')
{
arr[newLength-1] = '0';
arr[newLength-2] = '2';
arr[newLength-3] = '%';
newLength = newLength - 3;
}
else
{
arr[newLength-1] = arr[i];
newLength = newLength - 1;
}
}
System.out.println(arr);
}*
I dont understand why we need this line of code (newLength = newLength - 3), I think we need it because after we remove space with the symbol, we subtract 3 to go to the next empty space, is this correct?
That's correct, if you mean: to the next empty space to write a new character.
The codeline newLength = newLength - 3; exists because you need to skip 3 characters ('0', '2' and '%'). Else you would overwrite them.
I must mention that your code is quite typical since you are filling the array backwards.
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I'm writing a function in C (not C++, this is going to run on an older computer), which should take an input char* and add spaces to it, based on letter capitalization and numbers, then return the result. I cannot use strings and their functions I'm afraid, due to platform limitations.
For example, the input "TestingThisPieceOfText" should be returned as "Testing This Piece Of Text".
I have some (rather crude for now) code that works for simple cases like this, but I would like to add some exceptions to the rule, and that's where I need help:
If multiple capital letters are in a sequence, they should not be separated by spaces. For example, "APB" should stay as-is.
If there are numbers in the input string, there should be a space before (and after), but not between them. For example, "A10TankKiller2Disk" should be returned as "A10 Tank Killer 2 Disk".
Special-case for "Mc", to cover cases where such names might be sent in. For example, "ScroogeMcDuckIsFilthyRich" should be returned as "Scroodge McDuck Is Filthy Rich".
Here's the function as it currently stands (like I said, a little crude for now):
char* add_spaces_to_string(const char* input)
{
char input_string[100];
strcpy(input_string, input);
char* output = (char*)malloc(sizeof input_string * 2);
const char capitals[] = "ABCDEFGHIJKLMOPQRSTVWXYZ";
const char numbers[] = "1234567890";
const char mc[] = "Mc";
// Special case for the first character, we don't touch it
output[0] = input_string[0];
unsigned int output_index = 1;
unsigned int capital_found = 0;
unsigned int number_found = 0;
for (unsigned int input_index = 1; input_string[input_index] != '\0'; input_index++)
{
for (int capitals_index = 0; capitals[capitals_index] != '\0'; capitals_index++)
{
if (capitals[capitals_index] == input_string[input_index]
&& capital_found < input_index - 1
&& number_found < input_index - 1)
{
capital_found = input_index;
//printf("Found a capital character (%c), in position %u. Adding a space.\n", input_string[i], i);
output[output_index] = ' ';
output_index++;
output[output_index] = input_string[input_index];
}
}
for (int numbers_index = 0; numbers[numbers_index] != '\0'; numbers_index++)
{
if (numbers[numbers_index] == input_string[input_index]
&& capital_found < input_index - 1
&& number_found < input_index - 1)
{
number_found = input_index;
output[output_index] = ' ';
output_index++;
output[output_index] = input_string[input_index];
}
}
output[output_index] = input_string[input_index];
output_index++;
}
output[output_index] = '\0';
return output;
}
With the above, simple examples like
"AnotherPieceOfTextWithoutSpaces"
are correctly converted to
"Another Piece Of Text Without Spaces"
but more complex ones, like
"A10TankKiller2Disk"
are not - it returns
"A1 0Tank Killer 2Disk"
in that case.
So the question is, why am I getting spaces in the positions I don't want, while not getting them where I want (Based on the rules I mentioned above)?
Any pointers to the right direction would be greatly appreciated! :)
Edit: The detection of capitals and digits was more complex than necessary. Also, it would go in the routine of adding a space at the incorrect position, when a digit followed another digit, and when a capital letter followed a digit.
I rewrote the function, using 2 helper functions that were supported - isdigit() and isupper(). This seems to make it work for now:
char* add_spaces_to_string(const char* input)
{
char input_string[100];
strcpy(input_string, input);
char* output = (char*)malloc(sizeof input_string * 2);
const char mc[] = "Mc";
// Special case for the first character, we don't touch it
output[0] = input_string[0];
unsigned int output_index = 1;
unsigned int input_index = 1;
unsigned int capital_found = 0;
unsigned int number_found = 0;
while (input_string[input_index])
{
if (isdigit(input_string[input_index]))
{
if (number_found < input_index - 1)
{
output[output_index] = ' ';
output_index++;
output[output_index] = input_string[input_index];
}
number_found = input_index;
}
else if (isupper(input_string[input_index]))
{
if (capital_found < input_index - 1)
{
output[output_index] = ' ';
output_index++;
output[output_index] = input_string[input_index];
}
capital_found = input_index;
}
output[output_index] = input_string[input_index];
output_index++;
input_index++;
}
output[output_index] = '\0';
return output;
}
I still need to add an special rule for the case of "Mc", but that's a minor issue for me and I'll add it later.
I want to search for a block of characters (word) in a text.
For example, I have the next text "Hello xyz world", and I want to search for "xyz ", note the space after the word.
// The Text
const char * text = "Hello xyz world";
// The target word
const char * patt = "xyz ";
size_t textLen = strlen(text),
pattLen = strlen(patt), i, j;
for (i = 0; i < textLen; i++) {
printf("%c", text[i]);
for (j = 0; j < pattLen; j++) {
if (text[i] == patt[j]) {
printf(" <--");
break;
}
}
printf("\n");
}
The result must be like following:
But unfortunately, the result as the following:
It collects all the similar characters in the whole text, not just the target characters (the word).
How to fix that problem?
You have to do a full substring match before you print; mark the applicable characters on a first pass, and then have a second pass to print the results. In your case, you'd create a second array, with boolean values corresponding to the first, something like
text = "Hello xyz world";
match 000000111100000
I assume that you can find a basic substring match program online. Printing on the second pass will be easy: you already have the logic. Instead of if (text[i] == patt[j]), just use if match[i].
Is that enough of a hint?
You need to make sure that there is a full match before starting to print any <--. And to avoid to do accesses passed end of array on patt, you will have to stop searching when less than pattLen characters remain in array.
Then when you have found a full match, you can print the content of patt followed with <-- and increment position of pointer of pattLen-1. And at the end you will have to copy remaining characters from text.
Code could become:
// The Text
const char * text = "Hello xyz world";
// The target word
const char * patt = "xyz ";
size_t textLen = strlen(text),
pattLen = strlen(patt), i, j;
for (i = 0; i <= textLen - pattLen; i++) { // don't search if less that pattLen remains
printf("%c", text[i]);
if (text[i] == patt[0]) { // first char matches
int found = 1; // be optimistic...
for (j = 1; j < pattLen; j++) {
if (patt[j] != text[i + j]) {
found = 0;
break; // does not fully match, go on
}
}
if (found) { // yeah, a full match!
printf(" <--"); // already printed first char
for (j = 1; j < pattLen; j++) {
printf("\n%c <--", patt[j]);// print all others chars from patt
}
i += pattLen - 1; // increase index...
}
}
printf("\n");
}
while (i < textLen) {
printf("%c\n", text[i++]); // process the end of text
}
Above code gives expected output for "xyz " and also "llo"...
You should check every letter of your pattern from the beginning (and not check the whole pattern). Try this (not tested):
int currIndex = 0;
for (i = 0; i < textLen; i++) {
printf("%c", text[i]);
if (text[i] == patt[currIndex]) {
for (j = 0; j < pattLen; j++) {
if(text[i+j] != patt[j]){
continue;
}
}
printf(" <--");
currIndex++;
if(currIndex==pattLen)
currIndex = 0;
}
else{
currIndex = 0;
}
printf("\n");
}
Note: It is not the best way to achieve this but the easiest with your example
Note 2: This question should be closed as it is:
Questions seeking debugging help ("why isn't this code working?") must
include the desired behavior, a specific problem or error and the
shortest code necessary to reproduce it in the question itself.
Questions without a clear problem statement are not useful to other
readers. See: How to create a Minimal, Complete, and Verifiable
example.
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 have a program I wrote to take a string of words and, based on the delimiter that appears, separate each word and add it to an array.
I've adjusted it to account for either a ' ' , '.' or '.'. Now the goal is to adjust for multiple delimiters appearing together (as in "the dog,,,was walking") and still only add the word. While my program works, and it doesn't print out extra delimiters, every time it encounters additional delimiters, it includes a space in the output instead of ignoring them.
int main(int argc, const char * argv[]) {
char *givenString = "USA,Canada,Mexico,Bermuda,Grenada,Belize";
int stringCharCount;
//get length of string to allocate enough memory for array
for (int i = 0; i < 1000; i++) {
if (givenString[i] == '\0') {
break;
}
else {
stringCharCount++;
}
}
// counting # of commas in the original string
int commaCount = 1;
for (int i = 0; i < stringCharCount; i++) {
if (givenString[i] == ',' || givenString[i] == '.' || givenString[i] == ' ') {
commaCount++;
}
}
//declare blank Array that is the length of commas (which is the number of elements in the original string)
//char *finalArray[commaCount];
int z = 0;
char *finalArray[commaCount] ;
char *wordFiller = malloc(stringCharCount);
int j = 0;
char current = ' ';
for (int i = 0; i <= stringCharCount; i++) {
if (((givenString[i] == ',' || givenString[i] == '\0' || givenString[i] == ',' || givenString[i] == ' ') && (current != (' ' | '.' | ',')))) {
finalArray[z] = wordFiller;
wordFiller = malloc(stringCharCount);
j=0;
z++;
current = givenString[i];
}
else {
wordFiller[j++] = givenString[i];
}
}
for (int i = 0; i < commaCount; i++) {
printf("%s\n", finalArray[i]);
}
return 0;
}
This program took me hours and hours to get together (with help from more experienced developers) and I can't help but get frustrated. I'm using the debugger to my best ability but definitely need more experience with it.
/////////
I went back to pad and paper and kind of rewrote my code. Now I'm trying to store delimiters in an array and compare the elements of that array to the current string value. If they are equal, then we have come across a new word and we add it to the final string array. I'm struggling to figure out the placement and content of the "for" loop that I would use for this.
char * original = "USA,Canada,Mexico,Bermuda,Grenada,Belize";
//creating two intialized variables to count the number of characters and elements to add to the array (so we can allocate enough mmemory)
int stringCharCount = 0;
//by setting elementCount to 1, we can account for the last word that comes after the last comma
int elementCount = 1;
//calculate value of stringCharCount and elementCount to allocate enough memory for temporary word storage and for final array
for (int i = 0; i < 1000; i++) {
if (original[i] == '\0') {
break;
}
else {
stringCharCount++;
if (original[i] == ',') {
elementCount++;
}
}
}
//account for the final element
elementCount = elementCount;
char *tempWord = malloc(stringCharCount);
char *finalArray[elementCount];
int a = 0;
int b = 0;
//int c = 0;
//char *delimiters[4] = {".", ",", " ", "\0"};
for (int i = 0; i <= stringCharCount; i++) {
if (original[i] == ',' || original[i] == '\0') {
finalArray[a] = tempWord;
tempWord = malloc(stringCharCount);
tempWord[b] = '\0';
b = 0;
a++;
}
else {
tempWord[b++] = original[i];
}
}
for (int i = 0; i < elementCount; i++) {
printf("%s\n", finalArray[i]);
}
return 0;
}
Many issues. Suggest dividing code into small pieces and debug those first.
--
Un-initialize data.
// int stringCharCount;
int stringCharCount = 0;
...
stringCharCount++;
Or
int stringCharCount = strlen(givenString);
Other problems too: finalArray[] is never assigned a terminarting null character yet printf("%s\n", finalArray[i]); used.
Unclear use of char *
char *wordFiller = malloc(stringCharCount);
wordFiller = malloc(stringCharCount);
There are more bugs than lines in your code.
I'd suggest you start with something much simpler.
Work through a basic programming book with excercises.
Edit
Or, if this is about learning to program, try another, simpler programming language:
In C# your task looks rather simple:
string givenString = "USA,Canada Mexico,Bermuda.Grenada,Belize";
string [] words = string.Split(new char[] {' ', ',', '.'});
foreach(word in words)
Console.WriteLine(word);
As you see, there are much issues to worry about:
No memory management (alloc/free) this is handeled by the Garbage Collector
no pointers, so nothing can go wrong with them
powerful builtin string capabilities like Split()
foreach makes loops much simpler
I am trying to separate each word from a character array and put them into a pointer array, one word for each slot. Also, I am supposed to use isspace() to detect blanks. But if there is a better way, I am all ears. At the end of the code I want to print out the content of the parameter array.
Let's say the line is: "this is a sentence". What happens is that it prints out "sentence" (the last word in the line, and usually followed by some random character) 4 times (the number of words). Then I get "Segmentation fault (core dumped)".
Where am I going wrong?
int split_line(char line[120])
{
char *param[21]; // Here I want to put one word for each slot
char buffer[120]; // Word buffer
int i; // For characters in line
int j = 0; // For param words
int k = 0; // For buffer chars
for(i = 0; i < 120; i++)
{
if(line[i] == '\0')
break;
else if(!isspace(line[i]))
{
buffer[k] = line[i];
k++;
}
else if(isspace(line[i]))
{
buffer[k+1] = '\0';
param[j] = buffer; // Puts word into pointer array
j++;
k = 0;
}
else if(j == 21)
{
param[j] = NULL;
break;
}
}
i = 0;
while(param[i] != NULL)
{
printf("%s\n", param[i]);
i++;
}
return 0;
}
There are many little problems in this code :
param[j] = buffer; k = 0; : you rewrite at the beginning of buffer erasing previous words
if(!isspace(line[i])) ... else if(isspace(line[i])) ... else ... : isspace(line[i]) is either true of false, and you always use the 2 first choices and never the third.
if (line[i] == '\0') : you forget to terminate current word by a '\0'
if there are multiple white spaces, you currently (try to) add empty words in param
Here is a working version :
int split_line(char line[120])
{
char *param[21]; // Here I want to put one word for each slot
char buffer[120]; // Word buffer
int i; // For characters in line
int j = 0; // For param words
int k = 0; // For buffer chars
int inspace = 0;
param[j] = buffer;
for(i = 0; i < 120; i++) {
if(line[i] == '\0') {
param[j++][k] = '\0';
param[j] = NULL;
break;
}
else if(!isspace(line[i])) {
inspace = 0;
param[j][k++] = line[i];
}
else if (! inspace) {
inspace = 1;
param[j++][k] = '\0';
param[j] = &(param[j-1][k+1]);
k = 0;
if(j == 21) {
param[j] = NULL;
break;
}
}
}
i = 0;
while(param[i] != NULL)
{
printf("%s\n", param[i]);
i++;
}
return 0;
}
I only fixed the errors. I leave for you as an exercise the following improvements :
the split_line routine should not print itself but rather return an array of words - beware you cannot return an automatic array, but it would be another question
you should not have magic constants in you code (120), you should at least have a #define and use symbolic constants, or better accept a line of any size - here again it is not simple because you will have to malloc and free at appropriate places, and again would be a different question
Anyway good luck in learning that good old C :-)
This line does not seems right to me
param[j] = buffer;
because you keep assigning the same value buffer to different param[j] s .
I would suggest you copy all the char s from line[120] to buffer[120], then point param[j] to location of buffer + Next_Word_Postition.
You may want to look at strtok in string.h. It sounds like this is what you are looking for, as it will separate words/tokens based on the delimiter you choose. To separate by spaces, simply use:
dest = strtok(src, " ");
Where src is the source string and dest is the destination for the first token on the source string. Looping through until dest == NULL will give you all of the separated words, and all you have to do is change dest each time based on your pointer array. It is also nice to note that passing NULL for the src argument will continue parsing from where strtok left off, so after an initial strtok outside of your loop, just use src = NULL inside. I hope that helps. Good luck!