Questions tagged [c]

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Helping with Valgrind "Conditional jump or move depends on uninitialised value(s)" in simple C code

So right now my code seems to me like it doesnt have issues, it looks like this: int i; char hello[] = "Hello World!"; char * str = malloc(strlen(hello)+1); for(i = 0; i < ...
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pset4 blur, tried this method, I can't figure out what is the problem with my code

It compiles, and passes the check for pixels in the corner, but fails every other test, before I added the logic for the corners and edges it passed the test for the middle pixels also. I can't ...
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1answer
17 views

Use of undeclared identifier 'num'

I dont really know where im wrong. it gives me "use of undeclared identifier 'num'" i allready tried to solve it but i have no clue of what is going on #include <stdio.h> int maxc = 0,...
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2answers
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for- loop stop if output A

on pset2/caesar and only when ciphertext[i] = A or a for loop stopped ????
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Pset3: Tideman - Sort_pairs

Check50 says that my sort_pairs function is wrong, but with the tests I've used, everything is alright. Here's the code: void sort_pairs(void) { int biggest_strength_of_victory = preferences[pairs[0]....
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1answer
23 views

How to convert an unsigned char to a string?

I'm needing to collect byte by byte of an unsigned char and convert it to a string, how can I do that? I've tried everything but it didn't work. My example code: #include <stdio.h> #include <...
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1answer
17 views

Mario problem: Program got stuck at user input

// ** Below is the code of mario pset1, its taking input of width multiple times and not executing step after input// #include <cs50.h> #include <stdio.h> #include <math.h> int main(...
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22 views

Why do Escape Sequences in C work differently when I compile code by using GCC?

Why do Escape Sequences in C work differently when I compile code by using GCC? For example, Input: #include <stdio.h> int main(void){ printf("Hello world\n"); } Output in CS50 ...
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1answer
20 views

How does the CS50 IDE recognize C functions in advance?

I notice that functions like printf() and toupper() appear in blue without the relevant #include statements in files with names ending in .c. What is happening under the hood to make this happen?
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1answer
29 views

'stadio.h' file not found

#include <stadio.h> int main(void) { printf("hello, world"); } when i type make hello clang -ggdb3 -O0 -std=c11 -Wall -Werror -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-...
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1answer
23 views

Unable to confirm user input is a number using isdigit in c

My code is attempting to; take user input from the command line; check if the input is a whole number; confirm positively if so; confirm negatively if not; however all numbers return a negative ...
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1answer
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error : function definition not allowed here pls help

i got this error message pls help $ make triangle clang -ggdb3 -O0 -std=c11 -Wall -Werror -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable -Wshadow triangle.c -lcrypt -lcs50 -...
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1answer
13 views

pset2//caesar : strspn result

I'm struggling to understand : (argc != 2 || argv[1][strspn(argv[1], "1234567890")]) It works, but I'm trying to understand what's going on inside the if evaluation, and the value argv[1][...
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1answer
18 views

function output?

I can't get this function to output the desired value of 0.07. #include <stdio.h> #include <cs50.h> #include <math.h> float i = 1.32; float quar_val = 0.25; int func(float val, ...
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19 views

CS50 Speller: valgrind test says that bytes are still reachable in 3 blocks

I'm currently at the CS50's pset5, and am working on the "Speller" problem. I managed to do all functions and don't have any compile or runtime errors. When using check50, though, I receive ...
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1answer
35 views

pset4 filter blur less got stuck

i have been working on blur and it works just fine as i run it. but when i run check50 i get this : :( blur correctly filters middle pixel expected "127 140 149\n", not "145 160 169\n&...
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1answer
36 views

credit pset1 cs50 sum while loop

I was doing the credit problem with the visa test card in the page: 4003600000000014 It passed that test, however in other tests it doesn't pass. I think it's a matter of the sum that it can't compute ...
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0answers
11 views

Cannot Compile CS50 Library

I've been running into this problem lately. Here's one of my code: #include <cs50.h> #include <stdio.h> #include <string.h> // ... for (int i = 0; i < voter_count; i++) { ...
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0answers
8 views

Library = Collection of functions?

do I understand it right, that in that library there are only a collection of functions inside that i can use?
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1answer
17 views

Why is an Array longer then the input?

why we can access more information than the lenght of the array? I thought that after the Null (0) the array ends. Why we can access position 40?
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1answer
31 views

CS50 - PSET 4 - Filter - Edges

//Pixel buffer RGBTRIPLE pixelBuffer[height][width]; //Iterates on every pixel and calculates Gx and Gy for (int i = 0; i < height; i++) { for (int j = 0; j < width; j++)...
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0answers
6 views

Error with calculating Egdes in Pset4 Filter (More) Detect Edge problem

// Detect edges RGBTRIPLE new_pixel(int i, int j, int height, int width, RGBTRIPLE image[height][width]) { int redx; int bluex; int greenx; int redy; int bluey; int greeny; ...
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1answer
32 views

PSET4 RECOVERY does not recover images correctly

I have started working on PSET 4 RECOVERY. My program compiles successfully, it goes through the first 3 tests no problem, but for the love of me I cannot seem to find the problem. It just does not ...
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3answers
19 views

Error retrieving return values ​from a function

I am currently studying coding in C language and I have doubts about the return of functions, what I am trying to do is the following: Call the number () function and pass 3 values ​​of the integer ...
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1answer
20 views

Recover PSET4 Corrupt images

i was working on pset4 recover and my code finds all the image, but everytime it writes to the image the image got corrupted, and i cant find the issue, checked the debugger and it seems going the way ...
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1answer
25 views

Help to finish my problem - Check50 - Pset4 - Filter Less

I am coding the sepia filter, it is already working, but it does not pass the check50. I think of according to the check50 report, that there is some problem of precision in the calculations, but I ...
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1answer
49 views

pset4 - (Filter Less ) - Doubts with malloc()

I'm performing the problem set from pset4 to the (filter less) part. I wish to use malloc() to my advantage to speed up image filtering and maybe check50 will accept my solution to the problem. I ...
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1answer
46 views

Recover - segmentation fault and other general problems

Hey guys so I've hit a bit of a wall with Recover, when I run my program I get segmentation fault but I also don't know how to end off one jpeg when another header pops up? In essence, I'm not sure ...
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1answer
48 views

Lecture 5 Linked Lists: What's going on under the hood?

Sheepishly I must admit I am having difficulty understanding how Linked Lists are implemented. Spent an hour and a half just on this part. The following partial code is from the lecture (comments ...
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1answer
68 views

PSET3 Tideman - What to do with the lock_pairs function?

Can someone please help me with the lock_pairs section of the problem? The lock_pairs function is killing me. I get that you have to compare the pairs to each other and then return false or true in ...
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1answer
31 views

PSET 1 Credit Card Checksum doesn't add up

I'm having my issues finding the right answer as this is non code related. The checksum says: "If the total’s last digit is 0, the number is valid!" This is a credit card number that is ...
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1answer
21 views

question on Week 1 lecture

I just have a small question. David showed how to compile the source code "Hello.c" file using the make command to make the executable machine code file "Hello" in the lecture. I ...
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1answer
64 views

Credit (Pset1) - Checksum problem

so I have a problem with the Credit exercise from pset1. I updated my code today after realizing that I didn't split up the digits of the product of the current digit in the card number and 2 and ...
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1answer
11 views

Command debug not found

when I try to run the command debug debug ./scores the message that returns is that : Command 'debug' not found
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2answers
34 views

stuck on readability pset2

Hi I am stuck on readability and am not sure what i am doing wrong $ ./readability Text: one fish. two fish. red fish. blue fish 8 3 42 13 Grade 13 and my code: #include <stdio.h> #include <...
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1answer
487 views

Lab 8 // Resetting button colors not working properly

I am doing the lab 8 trivia question and I am try to reset all the colors of the buttons when you press another from the rest. I am not sure how to do it. I have the function for resetting the colors ...
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1answer
21 views

PSet3 Tideman , error with updating ranks array

bool vote(int rank, string name, int ranks[]) { for (int i = 0; i < candidate_count; i++) { if (strcmp(name, candidates[i]) == 0) { ranks[rank] = name; ...
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1answer
20 views

I have included all the libraries, yet it shows errors (pset2)

This is my code: #include <stdio.h> #include <cs50.h> #include <stdlib.h> #include <string.h> #include <ctype.h> int main (int argc, string ...
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2answers
49 views

Speller.c, get correct result on my machine, wrong on check50

Good day, I am struggling with speller.c. When I run the program on my machine I get the correct result compared to the keys but then when I use check50 to check I get all wrong. I have narrowed the ...
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2answers
61 views

Check50 accepts all but last 2 tests. pset1/credit

I've been trying to fix this on my own for a bit but I wasn't able to find an answer online. My credit program passes all check50 test's except for the last two (identifies 4111111111111113 as INVALID ...
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1answer
68 views

My do-while loop does not work

do { number = get_long_long("What is your credit card number? "); } while((number < 1000000000000) || (number >= 10000000000000000)); This loop is not accepting inputs. I do not ...
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2answers
36 views

What modification do I need to shorten my code?

I have come up with the following code to solve caesar.c of pset2. It passes all check50 tests. However, it fails to detect when a string input is not a number. The way I understand it, I have to ...
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1answer
22 views

Why is my if else statement not working?

Here's my Code: #include<stdio.h> #include<cs50.h> int main (void) { string a= get_string("Enter a name\n"); string b= get_string("Enter Class\n"); ...
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1answer
95 views

I don't understand the comments from check50 on my lab 1 submission. could anyone help please?

This is my code #include <cs50.h> #include <stdio.h> int main(void) { // TODO: Prompt for start size int s; do { s= get_int("Start size: "); } ...
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1answer
43 views

pset4 Blur calculation does not work properly

for some reason I can't get my calculation for the blur value running. The pictures are really odd and contain crazy colors. Any ideas to why this could be the case? I compared it already to working ...
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1answer
70 views

Mario less, struggling with nested FOR loop

hello I have got my code to work but don't understand logic, I found a flow cart for how nested for loops work and with that I was able to mix things around until I got it to output correctly but ...
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1answer
15 views

How can i arrange the output in decending order In this program? [closed]

#include <stdio.h> int main() { int n,i; printf("Enter a number: "); scanf("%d",&n); for (i=0; i<=n; ++i) { if (i%(7*13*19)==0) { ...
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1answer
18 views

Why is my get_positive_int code not working? (I seem to do everything right!)

Here's my code (written in C), I was trying to program this for a long time, and even when I just tried to copy the code directly from the video lecture, it's wrong! Please help me. Here's my code: #...
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1answer
7 views

Caesar - ASCII to char conversion problem

Going through the CS50 exercise Caesar, and I'm still very new to C. My code to validate the key is all working, but as I try to convert from plaintext to the cipher text I keep getting caught up with ...
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1answer
28 views

pset4 recover creates 50 images but bytes don't match up

My code creates the 50 files, all of them starting with the correct JPEG signature, however the rest of the bytes don't match up. In other words, first 4 bytes are correct, the following bytes are ...

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