I'm new to C, I've already searched and I haven't found an answer, but I've been trying to get the program to give me a list with the name of the products typed in by the user followed by the sum of all prices and I've found the error:

clang-7 -pthread -lm -o main main.c
/tmp/main-7440c0.o: In function `main':
main.c:(.text 0x12b): undefined reference to 'N'
main.c:(.text 0x164): undefined reference to 'Digitanome'
main.c:(.text 0x17f): undefined reference to 'Lista'
clang-7: error: linker command failed with exit code 1 (use -v to see invocation)
exit status 1

The code I've been trying is this one:

#include <stdio.h>
#include<stdlib.h>
#include <string.h>

extern char (N[][40]);
int i;
char p;
int cod,cont, soma2;
char soma[100];

int Digitanome( char [][40], int );
void Lista( char [100][40], int );

typedef struct {
char produto[30];
char seçao [30];
float preco;
int cargo;
}Supermercado;

Supermercado compra;

    
int main(void)
{
  char Nome[100][40] = { '\0' };
  int qtdNomes = 0;

  soma2 = 0;
  do{  
    printf("\n\nEm qual seção está seu produto?");
    printf("\n1-Frutas \n2-Doces \n3-Material de Limpeza\n -->  ");
    scanf("%d",&cod);
    if(cod == 1){
      *compra.seçao = *strcpy(compra.seçao,"Frutas");
    }
    if(cod == 2){
      *compra.seçao = *strcpy(compra.seçao, "Doces");
    }
    if(cod == 3){
      *compra.seçao = *strcpy(compra.seçao,"Material de Limpeza");
    }
    int Digitanome(char N[][40], int i);
    {
      printf("Informe o produto que você quer nesta seção: \n");
      scanf("%s", & *N[i]);

      *compra.produto = Digitanome( Nome, qtdNomes );
      Lista( Nome, qtdNomes );
      return   i;
    }
    return 0; 

    printf("Informe o preço do produto: \n");
    scanf("%f", &compra.preco);
    soma2 = soma2   compra.preco;
    printf("\nDeseja mais algum produto? \n4-Sim \n0-Não, sair \n -->  ");
    scanf("%d",&cont);
  }while(cont == 4);
  {
    if (cont == 0)
      printf("\nFIM DAS COMPRAS!\n");

    void Lista(char p[100][40], int i);{
      int j = 0;
      for (; j < i; j   )
        printf("\nSeus produtos são:%s\n", compra.produto);
    }
    printf("Essa compra está custando: %i \n", soma2);
  }
}

Can anyone explain to me what is happening and how to solve it?

CodePudding user response：

Several problems:

1. extern char (N[][40]);

You declare N as extern without initialization so you would also need to delcare it in another module with initialization. But you don't actually ever use the variable N. You have N[][40] as an argument to Digitanome. Once you fix item numbers 2 and 3 below, you can remove extern char (N[][40]); completely.

2. You define Digitanome and Lista inside main(). You need to define them outside of main().

3. You have semicolons at the end of Digitanome and Lista function definitions. You need to remove those.

4. You have code following the return 0 statement.

5. You call Digitanome from inside Digitanome. That is probably not what you want.

Once you fix those problems, you will probably find more.