Most voted "pointer" questions
The tag can be used for the concept applied to any language. A pointer is a type of data that "points to" another value stored in memory using its address.
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answer110
viewsI need an explanation why the C code gives a Segmentation fault error
I started my dynamic allocation studies but I’m not able to make a simple example, I couldn’t find the problem. #include <stdio.h> #include <stdlib.h> #define SUCESSO 1 #define FALHA -1…
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answer793
viewsHow to check whether the list is empty or with an element in C
typedef struct { int tamanho; nodo *inicio; } lista; typedef struct { lista **vet; int tamTabHash; int colisoes; } tabHash; tabHash…
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answer1497
viewsHow to edit data from a Struct using a function
I want to create an edit function that takes as a parameter the music array by reference. (using pointers) The user must choose the song number and type back the data from that vector position. I…
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answers176
viewsDynamic allocation with a void function
I made a simple code using dynamic allocation. Just ask for the vector size, to insert data and print them at the end I can make dynamic allocation with int, returning the vet, but as I’m learning,…
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answer549
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answers85
viewsMemory junk when pointing a pointer
In an attempt to implement an adjacent matrix graph, I created the function to create a new "matrix" in which the contents of the graph would be copied to it by adding the new positions. However,…
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answer38
viewsThe queue code has an error in the search. How can I fix it?
I use the search twice in my code and it is a binary search in order to respect the criteria imposed in the header of this exercise. But the doubt lies in the binary search module because the…
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answer90
viewsProblem with Segmentation fault with whole pointer
The program below attempts to reproduce a cellular automaton model. When I use "n" (number of cells) above 65 thousand, the program returns Segmentation fault. I tried to "print" some text in…
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answer57
viewsAccessing methods of a class on a vector of pointers
All right, I have a Package class with a public method double calculate_cost(). I need to create a std::map<string, std::vector<Package*>> where I can iterate through the array and save…
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answer88
viewsError referencing Struct with Pointers
I’m trying to convert this below algorithm into c language but I’m having trouble calling the variable and assigning a value to p.key=1 of the struct element. Error Code: error: request for Member…
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answers981
viewsChange a text value using a C pointer
I need to change the values of the variables through their pointers but I’m not getting. #include <stdio.h> #include <stdlib.h> //Programa principal int main() {//Declaração de variáveis…
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answer84
viewsReturn malloc to pointer does not stay between functions
I have these two examples here: example 1: void copiaStr(char *a,char *b){ b = (char *) malloc(strlen(a)); for(int i = 0; i < strlen(a) ;i++){ b[i] = a[i]; } } int main(){ char *a = "alou"; char…
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answers37
viewsRedefining how a function operates? C
Hello, I have a question regarding a line of code below, see: #include <stdio.h> typedef float (*TPonteiroFuncao)(float, float); // O QUE ESSA LINHA FAZ? float soma(float a, float b){ return…
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answers2087
viewsProblem with perfect number in C
I’m having trouble showing if the number is perfect, when I put in 6, it says it’s not perfect, and I can only use pointer and dynamic allocation. Someone would know how to help me? #include…
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answer559
viewsRequest for Member 'name' in Something not a Structure or Union - Error
#include <stdio.h> #define MAX_VETOR 6 const int na = 1; typedef struct { char nome[10]; char sexo[1]; } tp_pessoa; typedef struct { tp_pessoa *pessoas[MAX_VETOR]; int inicio,fim; } tp_vetor;…
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answers43
viewsI got an error trying to create my matrix. Error: Warning Passing argument 1 of " " from incompatible Pointer type
I’m trying to create a code with a 3x3 matrix. However, I haven’t touched C for a while and I needed to review this content. I believe that the failure of the program is some question related to…
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answer73
viewsWhy are the values of x and v[0] not equal? - C language
I’m reviewing some concepts on the site : Addresses and Pointers, until I find the following code: void func1 (int x) { x = 9 * x; } void func2 (int v[]) { v[0] = 9 * v[0]; } int main (void) { int…
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answer33
viewsList code not compiling well
Hello. I’m trying to learn about pointers and lists and I made a code that contains a menu and the option to enter as many values as I want. I made the code in the most recent codeblocks using W10…
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answer621
viewsVoid pointer in C
Write a program in C that reads 2 numbers (integer or real) and prints their sum. The user informs what type of data will be entered. Note: Use only pointers and dynamic memory allocation to solve…
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answers249
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answers189
viewsFunction to print the number of characters in a two-dimensional string
By the enunciation of the exercise, I must use as the second argument char **strings, I believe that there is my confusion, in manipulating her to count the size of string. (I did other tests with…
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answers173
viewsError Segmentation fault(core dumped) in C
When trying to calculate which prime can make a division of rest 0 with the number 600851475143 I came across the error segementation fault(core dumped) (although I used the sieve of Eratosthenes…
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answer204
viewsHello, I’m trying to do a data structures exercise in c, but there’s an error and I can’t find it. Follow the statement and the code
4. Write in C a system for enrollment and visualization of students. /// To store all students, implement a dynamic vector of pointers for structs, with a size of 100 records #include<stdio.h>…
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answer35
viewsSegmentation failure using realloc function
Hello, I have a function that should receive values from an intersection and if you enter a value I should relocate more memory and return this pointer. Analyzing the problem, it seems to me to be…
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answer51
viewsVector pointer with dynamic allocation in C
I managed to do this exercise inside main, however the same concept has not worked when using functions. The aim of the program is simple, read six values and display them. #include <stdio.h>…
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answer50
viewsSegmentation failure - C
#include <stdio.h> #include <stdlib.h> #include <string.h> int validaTipo(char t); typedef union{ struct contratoIndividual{ unsigned int…
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answers41
viewsBug in AVL tree implementation
I’m trying to implement an AVL tree, but when I call the Inserts function in the main and step some value(int) happens something strange. The first time the if (of the Inserts function) is…
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answer297
viewsC CHAR reading that works with %s but not with %c, why? And how does INCREMENT work on a pointer?
I hosted the code complete in the Pastebin: https://pastebin.com/feKaxAiz. It is a matrix where it is possible to perform the SUMMING UP or AVERAGE of the elements above the MAIN DIAGONAL. It is…
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answers103
viewsC Pointer Vector Search
Consider a type that represents an employee of a company, defined by the following structure: typedef struct funcionario Funcionario; struct funcionario { char nome[81]; // Nome do funcionário float…
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answer51
viewsStack algorithm problem in C (Struct and function do not "recognize")
Hello, I’m starting in the study of data structures and one of the algorithms passed is for data increment in a vector as in a stack (ie, the last incremented is the first to come out) I am in the…
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answers40
viewsRelate a user input to a class pointer
I would like to relate the class pointer corresponding to the user input and present on the screen the attributes related to that object. #include <iostream> #include "classes.h" using…
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answers30
views"Dereferencing NULL Pointer" error in a chained list structure
My code deals with a simple endadeada list (then I will implement the pointer to turn double). But in the line strcpy_s(new_element->musica_name, musica_name); He keeps giving an…
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answer36
viewsDelete queue element and release memory for this function?
I’m starting to understand pointers better and I’m implementing a queue, and it follows the function: FILA *removeNodeFIFO(FILA **raiz) { FILA *aux = *raiz; if (aux == NULL) { return NULL; } else {…
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answer35
viewsCan someone help me? I need to write a "reverse" function that reads the inverse of the vector using pointers. Example: typed 123, printed 321
#include <stdio.h> #include <stdlib.h> void inverte (int *original, unsigned int qtd, int *invertido){ } int main() { int qtd; int…
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answers152
viewsOrdering values by pointers
Good, I was doing an exercise that asked to read 3 real numbers, order them and show in an orderly way. I thought making a function that uses pointers would be a good idea, but the program always…
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answer48
viewsin C. I passed a vector to a function and changed it inside. Why didn’t you change my vector in the main function? because I passed a pointer
#include <stdlib.h> void matriz_transposta( int l, int c, int *matriz); int main (void){ int linha = 2, coluna = 2; int *mat = (int*)…
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answer222
viewsPrint array of names in C++
I’m having trouble printing an array that has as elements a char 'Name' saved. When I print these elements, only the last letter of the char leaves, in this case, the letter 'and', and not the whole…
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answer61
viewsCall function to allocate vector in C
Hello, I’m creating a program to call a function that should allocate a vector to be used in main(), but I’m having difficulty, I imagine I should use a pointer to pointer, but I don’t have much…
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answers77
viewsMemory allocation with malloc()
Doubt 1: The pont should reserve a memory block for 1 integer which was requested on malloc(), but he reserves 32 bytes or a memory block for 8 integers. 'Cause he does it? Doubt 2: If I make one…
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answers27
viewsPointer matrix with no type and variable size in C
I am creating a game for my college work and need to read a txt file to build a level (phase) of the game. The txt example can be accessed here: https://pastebin.com/f778Ucxa. The dash represents an…
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answer56
viewsHow do I pick up two values obtained in a function through pointers?
I am building a program, whose enunciation is to make the user provide 20 numbers and these are analyzed as pairs or odd. In this case, the intention is to create a vector A that takes 20 integers…
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answer65
viewsHow to pass a char vector * (*) to a function?
Guys, I have this code: #include <stdio.h> void exibir_nomes (char *nome) { for (int i=0; i<5; i++) printf("Nome[%d] = %s\n", i, *nome); } int main () { char…
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answer38
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answer49
viewsHelp in function with pointers
Can anyone help me with this code ? not working, can’t find the error. #include <stdio.h> int chamar(int *n){ printf("Digite o valor de n:"); scanf("%d",&n); printf("%d",n); return 0; }…
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answers171
viewsAdd a char on a char pointer in C/C++
I need to add a char on a pointer of char. For example: I have a pointer of char called name, which receives "log", after the process, I want it to be "log1". I tried to implement it like this, but…
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answer438
viewsHow to pass a pointer inside a struct per function parameter?
The situation is as follows: I have a struct with a field that is a pointer pointer, however I want to pass as parameter in a function only the pointer pointed, that is, the innermost pointer of…
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answer317
viewsFunction with pointer to pointer
I have the following function NOTE: In this function is only the first case, so it doesn’t get too big. Since the error occurs right at the first insertion. int insertAVL_TreeR(struct AVL_TreeNode…
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answer450
viewsHow to do a pointer struct for a function that prints the struct itself in C
I have a structure: struct conteudo{ tipo valor; //valor qualquer void (func*)(void*); //ponteiro para função que imprime a propria estrutura }; I would like to know how to call this function to the…
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answer28
viewsWhy am I making a mistake adding two numbers using pointers?
#include <stdio.h> int* adicionar(int *a,int *b) { int c = *a + *b; return &c; } int main() { int primeiro, segundo; int* temp; scanf("%d%d",&primeiro, &segundo); temp =…
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answers64
viewsIncrement does not work as expected
I took this exercise and put it to compile, but it’s going wrong I think because the values I see would be 5 and 9, but it’s going 6 and 8, I believe the IDE is not reading correctly. #include…