I have been writing a program to input a phrase and turn it into an acronym. For some reason when I output my acronym at the moment it comes out with a bunch of random characters. How do I fix it?
#include <stdio.h>
#include <string.h>
#define MAXLEN 50
int main() {
int num;
printf("Enter number of acronyms to add to the database:");
scanf("%d", &num);
getchar();
char strings[num][MAXLEN];
char acronym[num][MAXLEN];
for(int i = 0; i < num; i++){
printf("Enter the string to convert into an acronym:");
fgets(strings[i],MAXLEN,stdin);
printf("%s\n", strings[i]);
for(int j = 0; j < 11; j++){
if((strings[i][j]) >= 'A' && (strings[i][j]) <= 'Z'){
char buffer[][20] = {strings[i][j]};
strcat(acronym[i], buffer[i]);
}
}
puts(acronym[i]);
}
return 0;
}
I have tried changing the MAXLEN value to see if it was a memory issue or like a buffer overload. I've also just tried changing around how the strings switch and work together but nothing has worked.
char buffer[][20] = {strings[i][j]};
Here you let the compiler count how many elements the array has from the initialization.
It has 1 element, A string with single a single character strings[i][j] and rest of the 20 byte array filled with 0.
strcat(acronym[i], buffer[i]);
Here you access buffer[i], but there is only one string there (as explained above), so this is invalid if i is anything but 0.
I'm not sure what you are trying to do, but this would be valid implementation of what this code tries to do:
// extract single character as a string
char buffer[2] = {strings[i][j], 0}; // only one of 2 and 0 is mandatory
// append it to acronym
strncat(acronym[i], 20, buffer);
Probably lots of other stuff there is wrong, but here is one definite issue and a possible solution.
Related
I am making a program which requires the user to input an argument (argv[1]) where the argument is every letter of the alphabet rearranged however the user likes it. Examples of valid input is "YTNSHKVEFXRBAUQZCLWDMIPGJO" and "JTREKYAVOGDXPSNCUIZLFBMWHQ". Examples of invalid input would then be "VCHPRZGJVTLSKFBDQWAXEUYMOI" and "ABCDEFGHIJKLMNOPQRSTUYYYYY" since there are duplicates of 'V' and 'Y' in the respective examples.
What I know so far is, that you can loop through the whole argument like the following
for (int j = 0, n = strlen(argv[1]); j < n; j++)
{
//Place something in here...
}
However, I do not quite know if this would be the right way to go when looking for duplicates? Furthermore, I want the answer to be as simple as possible, right know time and cpu usage is not a priority, so "the best" algorithm is not necessarily the one I am looking for.
Try it.
#include <stdio.h>
#include <stddef.h>
int main()
{
char * input = "ABCC";
/*
*For any character, its value must be locate in 0 ~ 255, so we just
*need to check counter of corresponding index whether greater than zero.
*/
size_t ascii[256] = {0, };
char * cursor = input;
char c = '\0';
while((c=*cursor++))
{
if(ascii[c] == 0)
++ascii[c];
else
{
printf("Find %c has existed.\n", c);
break;
}
}
return 0;
}
assuming that all your letters are capital letters you can use a hash table to make this algorithm work in O(n) time complexity.
#include<stdio.h>
#include<string.h>
int main(int argc, char** argv){
int arr[50]={};
for (int j = 0, n = strlen(argv[1]); j < n; j++)
{
arr[argv[1][j]-'A']++;
}
printf("duplicate letters: ");
for(int i=0;i<'Z'-'A'+1;i++){
if(arr[i]>=2)printf("%c ",i+'A');
}
}
here we make an array arr initialized to zeros. this array will keep count of the occurrences of every letter.
and then we look for letters that appeared 2 or more times those are the duplicated letters.
Also using that same array you can check if all the letters occured at least once to check if it is a permutation
I don't know if this is the type of code that you are looking for, but here's what I did. It looks for the duplicates in the given set of strings.
#include <stdio.h>
#include <stdlib.h>
#define max 50
int main() {
char stringArg[max];
int dupliCount = 0;
printf("Enter A string: ");
scanf("%s",stringArg);
system("cls");
int length = strlen(stringArg);
for(int i=0; i<length; i++){
for(int j=i+1; j<length; j++){
if(stringArg[i] == stringArg[j]){
dupliCount +=1;
}
}
}
if(dupliCount > 0)
printf("Invalid Input");
printf("Valid Input");
}
This code snippet is used to count the duplicate letters in the array.
If you want to remove the letters, Also this code snippet is helpful .Set null when the same characters are in the same letter.
#include <stdio.h>
#include <stdlib.h>
int main()
{
int count=0;
int array[]={'e','d','w','f','b','e'};
for(int i=0;i<array.Lenth;i++)
{
for(int j=1;j<array.Length;j++)
{
if(array[i]==array[j])
{
count++;
}
}
}
printf("The dublicate letter count is : %d",count);
}
I'm trying to write a program to take 10 words as input from the user, then store it an array, and then print out the length of each word.
Here's my code:
#include <stdio.h>
#include <string.h>
char *words[10];
char length[10];
int i, j;
int main()
{
printf("Input ten words: \n");
for(i = 0; i < 10; i++)
{
printf("Enter element %d \n", i + 1);
scanf("%s", &words[i]);
}
for(i = 0; i < 10; i++)
printf("%c", words[i]);
for(i = j = 0; j < 10; j++)
{
length[j] = strlen(words[i]);
i++;
}
for(j = 0; j < 10; j++)
printf("%c", length[j]);
return 0;
}
It should be noted that I have no idea why the array "words" is defined as a pointer, I only do it because if I don't I get some warning about making a pointer from integer without a cast.
When I run the program what happens is, I get prompted to input the 10 elements, that much works, but then when it's supposed to print the "words" array, the program just crashes.
Also the reason I coded it like this is because later on I also need to print the longest and shortest word - so I figured it would help if I had the lengths of all the strings in their own array.
Does anyone know what's wrong here?
Thanks
With the line char *words[10], you are declaring an array of 10 pointers. However, these pointers are uninitialized, which means they are wild pointers. Dereferencing a wild pointer causes undefined behavior (i.e. the program may crash). If you want to use these pointers in a meaningful way, you must make each pointer point to a valid memory location, for example to an address returned by the function malloc or to the address of a char array.
However, probably the easiest solution to your problem is to not use pointers at all, but to instead declare a two-dimensional char array, like this:
char words[10][100];
That way, you are allocating space for 10 words of up to 100 characters each (including the null terminating character).
Beware that a buffer overflow will occur if the user enters a word longer than 99 (1 byte is required for the terminating null character). Therefore, the scanf line should be changed to the following:
scanf("%99s", words[i]);
That way, scanf will never attempt to write more than 100 bytes (including the terminating null character).
I have also removed the & in the scanf line above, because the & is not necessary, since words[i] will automatically decay to &words[i][0].
Also, as a general rule, you should verify that the return value of scanf is 1 before attempting to use the value that scanf wrote. For example, if the user triggers end of file on the input stream (for example by pressing CTRL-D on Linux or CTRL-Z on Windows), then scanf will return -1 without writing anything into words[i]. In that case, by subsequently reading from words[i], your program will cause undefined behavior.
Additionally, the line
printf("%c", words[i]);
must be changed to:
printf("%s", words[i]);
The loop
for(i = j = 0; j < 10; j++)
{
length[j] = strlen(words[i]);
i++;
}
can be simplified to:
for(i = 0; i < 10; i++)
{
length[i] = strlen(words[i]);
}
The line
printf("%c", length[j]);
should probably be changed to
printf("%hhu", length[j]);
because length[j] does not represent the ASCII code of a character, but just a number.
#include <stdio.h>
#include <string.h>
int main() {
char str[100];
int h[26]={0};
int i, j, count, tmp=0;
scanf("%s", str);
count=strlen(str);
for(i=0; i<count; i++) {
h[str[i]-97]++;
}
for(j=0; j<25; j++) {
if(h[j]<h[j+1]) {
tmp=j+1;
}
}
printf("%c", (char)tmp+97);
}
I want to output the most frequently entered lowercase letters, but how can I change it by output the strange values?
Try input this code "aaaabbbbsefa", then the "s" will be output.
Your code has a lot of problems. And a good bit of traps.
scanf("%s", str);
What if the input is longer than str can hold?
count=strlen(str);
This is a waste of cpu cycles. You don't need the length of a string to loop through it, you can simply check if the current element of the string is a \0
for(i=0; i<count; i++) {
h[str[i]-97]++;
}
This is problematic, what if the input contained some other character than lower case characters, this could easily cause out of bounds reading.
for(j=0; j<25; j++) {
if(h[j]<h[j+1]) {
tmp=j+1;
}
}
Firstly, this loop stops before 25, but it should stop before 26
Secondly, this definitely does not do what you think it does.
If you want to print the most frequent lower case character from in your input, this is how the flow should look like-
Take the string input and store it into a char array, make sure it can actually hold it
Declare a variable to keep track of the number of occurrences for each lowercase alphabet
Loop through the input string
Check if the current element is lowercase - if it is, add to the counter - if it isn't, do nothing
Loop through the occurrences record, check if the current occurrence is higher than the highest record (which is set to 0 before the loop) - if it higher, change the highest record to it and store the character - if it isn't, move on
Print the resulting character
This is how that'd look like in C-
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#define ALPHABET_COUNT 26
#define MAX_LEN 100
int main()
{
char str[MAX_LEN];
int occurrences[ALPHABET_COUNT] = { 0 };
if (!fgets(str, MAX_LEN, stdin))
{
// Something went wrong, error handling here
return 1;
}
for (int i = 0; str[i] != '\0'; i++)
{
if (islower(str[i]))
{
occurrences[str[i] - 'a']++;
}
}
int highest_occurrence = 0;
char highest_occurring_char;
for (int i = 0; i < ALPHABET_COUNT; i++)
{
if (occurrences [i] > highest_occurrence)
{
highest_occurrence = occurrences[i];
// Convert the current index to its corresponding lowercase alphabet
highest_occurring_char = (char) (i + 'a');
}
}
printf("Highest occurring character: %c\n", highest_occurring_char);
}
I'm fairly new to coding and am currently taking a programming course at school with C. We were given an assignment and I'm having a bit of difficulty with the first part. We're learning how to use the string-handling library (stdlib.h) and the objective of the assignment is to input multiple lines of text from the keyboard. The instructor advised us to use two-dimensional arrays in order to do this, but I'm a bit stuck. Here's the code I've written:
int main(void) {
char string[3][SIZE];
int i, j;
int c;
printf("Enter three lines of text:\n");
for (i = 0; i < 3; i++) {
j = 0;
while ((j < SIZE) && (c = getchar() != '\n')) {
string[i][j] = c;
j++;
}
}
for (i = 0; i < 3; i++) {
for (j = 0; j < SIZE; j++) {
printf("%c", string[i][j]);
}
printf("\n");
}
return 0;
}
Some points that I'd like to make are that I used the getchar() function to receive input one character at a time, and also the second for loop I intended to print each line of text that is stored in each row of the string array.
The input is any string of text for three lines, for example:
Hi my name is John.\n
I am from the US\n
and I'm a student.
Here's what the current output looks like:
Enter three lines of text:
rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr...
The output that I'm expecting is:
Enter three lines of text:\n
Hi my name is John.\n
I'm from the US\n
and am a student.
Any tips or advice would be greatly appreciated. Thank you!
First of all let me commend the fact the you starting your way with C. That's the most solid language to learn(better is only assembly itself) - you will have a full understanding of how things work, which you wouldn't get if started from some language written on top of C(like Java and Python).
But it's a hard and long road, which worth that.
On the code: there is a lot going and you have made a lot of amusing bugs that would reproduce different interesting things every other time and machine you run it.
First of all: to make your code work somehow all you need is add parenthesis:
while ((j < SIZE) && ((c = getchar()) != '\n')) {
In C everything is binary(or integer, depending how you look at it) and default binding is to the right a op1 b op2 c op3 d..
First op3 is evaluated c op3 d = r1, then you have a op1 b op2 r1 and so on.
Thus you was comparing the value of getchar() with value of character '\n' - which are not equal, so you get TRUE (value 1) and store it in local variable c.
Next you still have some problems because of the way you initialized your array:
char string[3][SIZE];
What it does is simply "intrusts" 3*SIZE*sizeof(char) bytes of you process address space to a thing labeled "string". But that does not clear up all the remnants of previous live (of your program, or even before) on those bytes, so if it happens that SIZE in your program == 100 and you used to store your credit card on a real address memory (RAM) mapped to that region of your program memory you would see your credit card when you print it by printf - if you didn't overwrite those 300 bytes.
This may help you looking at it:
#include <stdlib.h>
#include <stdio.h>
#define SIZE 10
int main(void) {
char string[3][SIZE];
int i, j;
int c;
for(i = 0; i < 3; i++)
for(j = 0; j < SIZE; j++){
string[i][j] = 0;
}
printf("Enter three lines of text:\n");
for (i = 0; i < 3; i++) {
j = 0;
while ((j < SIZE) && ((c = getchar()) != '\n')) {
string[i][j] = c;
j++;
}
}
for (i = 0; i < 3; i++) {
for (j = 0; j < SIZE; j++) {
printf("%c", string[i][j]);
}
printf("\n");
}
return 0;
}
Also be aware that getchar() may behave lousy with input and newlines - it depends on whether you console buffers input before sending it to your program on enter(newline) or not. More here How to avoid press enter with any getchar()
Note: I wrote this answer before the OP clarified they had to use getchar.
To read a whole line at a time, use fgets. To print a whole string at a time, use printf with the %s format.
#include <stdio.h>
int main(void) {
// No need to define a SIZE constant.
// Because it's stack allocated we can its size.
char strings[3][100];
printf("Enter three lines of text:\n");
for ( int i = 0; i < 3; i++) {
// Reads one line, up to the size of `strings[i]`, from stdin.
fgets( strings[i], sizeof(strings[i]), stdin );
}
for ( int i = 0; i < 3; i++) {
// Print each string and its line number.
printf("Line %d: %s\n", i, strings[i]);
}
return 0;
}
This is not the best pattern to read input. You'll learn very quickly that fixed memory sizes and reading input don't work well. For future reference, it would be more like this.
#include <stdio.h>
#include <string.h>
int main(void) {
// A list to store 3 strings, but no memory for the strings themselves.
char *strings[3];
printf("Enter three lines of text:\n");
// A line buffer that's sufficiently large.
// This will be reused.
char line[4096];
for ( int i = 0; i < 3; i++) {
// Read into the large line buffer.
fgets( line, sizeof(line), stdin );
// Copy the string into a buffer that's just big enough.
strings[i] = strdup( line );
}
for ( int i = 0; i < 3; i++) {
printf("Line %d: %s\n", i, strings[i]);
}
return 0;
}
This allocates a single large line buffer to do the reading, then copies what its read with strdup to memory of just the right size. This lets you read even very long lines of input without wasting a bunch of memory if they're very short.
Note that strdup() is not part of the C standard library, but it's part of the POSIX spec. Any major compiler will have it, and it's easy to write your own.
The objective of my assignment is to take in user input string and then print out the English alphabetic characters (both lower case and upper case) that the user has entered.
For example if the user inputs:D_!an!_ i12el the output would be Daniel.
My approach was to loop through the input and just remove all the non alpha characters but I dont know how to.Please help with any ideas! This is what I have so far:
#include <stdio.h>
#include <string.h>
int main()
{
char my_array[100];
printf("Enter a message: ");;
while(strlen(gets (my_array)) == 0);
printf(" Your message is: %s\n", my_array);
for(int i = 0; i< strlen(my_array);i++)
{
if(my_array[i] < 'A' || my_array[i] > 'z')
{
my_array[i] = ' ';
}
}
printf(" Your new message is: %s\n", my_array);
}
EDIT:I got my loop working to print out only the alpha characters but it keeps adding extra characters when i print the elements. For example D_!a_*&Ni#32el becomes DaNielASCIIV. I dont know why this is happening.
for(int i = 0; i< 100;i++)
{
if (isalpha(message[i]))
{
putchar(message[i]);
}
}
Rather than trying to update the string you have, just print out a character if it's a letter.
Also, upper case and lower case characters don't immediately follow one another, so you need to check for them separately:
printf(" Your new message is: ");
for(int i = 0; i< strlen(my_array);i++)
{
if((my_array[i] >= 'A' && my_array[i] <= 'Z') ||
(my_array[i] >= 'z' && my_array[i] <= 'z'))
{
putchar(my_array[i]);
}
}
printf("\n");
Alternetely, you could replace the above if condition with a function that checks for this:
if (isalpha(my_array[i]))
EDIT:
The reason you're now seeing extra characters is because you changed the loop to loop over the entire array instead of the length of the string. Go back to using strlen(my_array) instead of 100 and you'll be fine.
Use this pattern for removing elements from an array
int i, j;
j = 0;
for (i=0;i<N;i++)
if (good(array[i]) )
array[j++] = array[i];
N = j;
We go through, adding everything that matches. It's efficient and in-place.
It might be better to loop through the input string and use strchr() to see if the characters are in the string "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz". This has the advantages of not relying on a specific ordering for of the letters of the alphabet (see here and here), and being flexible so that you can easily change the characters that you want to pick out. You could then collect the results in a string, or print the filtered characters out directly.
char my_array[100];
char filtered_array[100];
char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz";
char *pchar;
int j = 0;
...
for (int i = 0; i < strlen(my_array); i++)
if ((pchar = strchr(alphabet, my_array[i])) != NULL) {
filtered_array[j] = *pchar;
++j;
}
filtered_array[j] = '\0';
...
The above code collects the results in a string. Note that a null-terminator is added to the end of filtered_array[], since this character would not be copied to the new array. If you want to include spaces or hyphens in the filtered string, just add these characters to the alphabet[] string.