Saving and printing from struct in C

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• Pushable Array in C

  Hello all I would like to know if there's a method whereby is similar to the array.push() method in javascript. I really want to create an array which allows the user to input an email into the array and each time a new email is inputted the array size is increased by 1.
• 1d heat transfer help using C to solve heat at a node

  attempting to write code for a maths problem whilst learning C but I'm a bit out of my depth. The problem is to calculate the time for the rod to cool down from set temp U whilst no heat is applied to ends and to reach a final temp of 0.2units. dx is distance between nodes and total nodes is N= 1 + (1 / dx).

  ui(t+dt)=ui(t) + 0.5*(ui)-(2*u(i)+u(i); where dt=0.5(dx)^2

  so far I have what is below(some taken from here https://www.codewithc.com/c-program-for-solution-of-heat-equation/?fbclid=IwAR1rVXDk9-LbjDKQAF2SmcmtfuZmvht25o_yy0Djjat4DZHz__4cwmB2jwo) , but clearly it is far from done:

  #include<stdio.h>               /* printf, scanf, puts, NULL */
  #include<math.h>                /* for long numbers
  #include <cmath>                /*for power function etc.. */
  
  #define X
  #define U                        /* this should be done from input files unlike in example where figures would be shown like X 1.0
  
  
  
  /*total nodes, define dx
  N = 1 + (1 / dx)
  dx = X step amount from input file 
  
  /* run the problem x times for different values of delta t until 0.1 heat units*/
      for (l = 0; l < x; l++) {
  
  /*specify initial conditions?
  u(i)=0
  u(i)=U(1=xi)
  etc
  
  
  float fun(int a)
  {
      return(INSERT X equation);
  }
  main()
  {
      float u[X+1][T+1], h=1.0, k=0.1,c,al,us,ue;
      int j,i;
      printf("\n Enter the square of 'c' :");
      scanf("%f",&c);
      dt=0.5(dx ^ 2);
      printf(" Enter the value of u[0, t] :");
      scanf("%f",&us);
      printf("  Enter the value of u[%d,t]:", X);
      scanf("%f",&ue);
      for(i=0;i<=T;i++)
      u[0][i]=u[X][i]=us;
      for(j=1;j<=X-1;j++)
      u[j][0]=fun(j);
      for(i=0;i<=T-1;i++)
      for(j=1;j<=X-1;j++)
      u(i+dt,j)=u(i,j) + 0.5*(u(i,j+1)-2*u(i,j)+u(i,j-1));
      printf(" The value of alpha is %4.2f\n",al);
      printf(" The value of u[j,i] are:\n ");
      for(i=0;i<T;i++)
      {
          for(j=0;j<X;j++)
          printf("%7.4f\t",u[j][i]);
          printf("\n");
      }
      }
  
  
  
  
  
  /* produce the output */
          filenum = fopen(filename[l][0], "w");
          fprintf(filenum,"TitleText: Heat over Delta Time: %e\n",
              deltat[l]);
          fprintf(filenum,"XUnitText: Distance\nYUnitText: Heat\n");
          for (i = 0; i < TIMESTEP; i = i + PLOTINC) {
              fprintf(filenum,"\"Time index: %d\n",i);
              for (j = 0; j < SIZE; j++)
                  fprintf(filenum,"%d %e\n",j, solution[i][j]);
              fprintf(filenum,"\n");
              }
          fclose (filenum);
      }
  
• How to name nested struct?

  I have two nested struct.

  One is an example from textbook, and another is from the project that I'm working on.

  The way of how example name struct is very good.

  On the other hand, another is very messy.

  This is the example struct:

  typedef struct{
      char firstName[ 20 ];
      char lastName[ 20 ];
      int age;
      char gender;
      double hourlySalary;
  }Employee;
  
  typedef struct{
      employee Andy;  
  }Company;
  
  Employee Andy;
  Andy.age = 40;    //Andy(type of employee)'s age(type of int) is 40
  
  Company Microsoft;
  Microsoft.Andy.age = 40;   //Microsoft(type of company)'s
                             //Andy(type of employee)'s 
                             //age(type of int) is 40
  

  This is the struct from the project:

  typedef struct
  {
      int length;
      int version;
      char name[200];
  }header;
  
  typedef struct
  {
      header flash;    //the header is used to search data in flash memory
  }component;
  
  component DSP;          //DSP is a component
  DSP.flash.version = 2;  //DSP(type of component)'s
                          //flash(type of header)'s
                          //version(type of int) is 2
  

  The logic above is wrong. DSP does not have a flash.

  component is a data type where its members needs to be saved in flash.

  The header(length, version and name) is used to search this component in flash memory.

  What I want to do is like:

  DSP.header.version = 3;    //DSP's header's version is 2
  

  But the way of this naming doesn't make sense.

  typedef struct
  {
      header header;
  }component;
  

  It seems an easy problem but I cannot figure it out. Where is my logic wrong?
• Save zip file to directory with Node JS, Electron, VueJS, Axios

  I'm trying to save (and extract) a zip file from a remote server to the local machine ( inside the temp folder) using Node, Electron, VueJS and axios.

  The closest i can do is let the user select a directory ( as if using the "Save as" function. ) but this needs to be done in the background. There were some somewhat similar questions posted, but none of which have been of use due to lack of explanation or having a different purpose.

  The server is working correctly, and when this is working i will add security measures.

  If you have any answer, please elaborate on it.

  Current steps:

  • Defining a folder within the temp dir.
  • Creating / clearing the folder ( It will be used multiple times ).
  • Setup request using Axios .

  • Take the data, and place it in a blob.

    runDownload: function(){
    //Getting the full path of where my file needs to go
    var dir = os.tmpdir() + '\\folder-in-temp-dir';
    
    //Create the folder if it does not exist.
    this.createFolder(dir);
    
    //Clear the folder of its contents
    this.clearFolderContents(dir);
    
    //Setup the request using Axios
    let req = this;
    var url = this.server+'files/index.php';
      this.$axios({
      url: url,
      method: 'GET',
      responseType: 'blob',  
      }).then((response) => {
    
        //Here is where things get blurry.
        file = response.data;
      });
    }
    
• Can't read a name from a file if it is made of letters

  Using VScode + code runner extension

  Once input() function receives a string like "qwe", program returns "NameError: name "qwe" is not defined" If input receives a string of numbers like "123", everything goes well. All files exist in right directory,and named/formatted pretty fine. Example of function:

  def maker():
      fileVar = str(input())
      fileVar = lineFixer(fileVar)
      with open(fileVar+".csv","r") as workfile:
          for line in workfile:
              return(line)
  

  lineFixer is a dumb function for some cases (has no influence on result):

  def lineFixer(line):
      line = line.strip('\n')
      line = line.strip('\t')
      line = line.replace('\n','')
      line = line.replace('\t','')
      return line
  

  Without str(input()), it's rubbish.
• Windows user allow write file with specific name

  Is it possible to allow specific user in Windows for specific folder:

  1. read any file
  2. delete any file
  3. write (create) files only with specific name like ABC*.TXT (for example ABC123456.TXT)

  This user connects to FTP on Windows Server 2012. User has access to specific folder and I want to deny him to write files except ABC*.TXT (other TXT files should be denied). I can't find any kind of solution in folder properties. Is it possible to do so? Or do I need some additional software?

  Thanks
• c++ string manipulation with pointers, null in middle

  I have to write a c++ function with the following specifications:

  unique

  Deletes the duplicated charters between the two parameter pointers. The string remains on its original place.

  param first - pointer to the beginning of the string

  param last - pointer to the data after the last charter

  return - pointer to the first charater of the new data series

  If the input is "H\0elllo C+++++ +!#", the output is "H\0elo C+ +!#". I canot figure out how to ignore the terminating null in the middle. This is my best approach so far:

  char *sajat::unique(char *first, char *last){
  char* moving = first + 1;
  char* follower = first;
  
  while (moving != last)
  {
  char *sentinel = first; 
      if (*follower == *moving)
      {
      counter++;
      sentinel = follower; //here was the duplication
          while (follower != last)
          {
              *follower = *moving;
              follower++;
              moving++;
          }
          sentinel = follwer;
          moving = follower + 1;
      }
      moving++;         
      follower++;
     }
  return first - counter;
  }
  

  So this code is obviously wrong...but it can identify successfully the duplication. (I know it is homework and shame on me....but i have been trying to solve it for hours. Sorry for the messed up code.)
• Pointers in AVL Tree Rotation C++

  I'm trying to implement an AVL (left) rotation as: Example of left rotation

  For the node I use a struct:

  struct Node {
      int value;
      int balance;
      int height;
      Node* right;
      Node* left;
      Node* parent;
  };
  

  And here my code for the rotation:

  void AVL::left_rotation(Node* &y) {
      Node* T2 = y->right->left;
      Node* x = y->right;
      x->left = y;
      y->right = T2;
      if (y->parent != NULL) {
          x->parent = y->parent;
          if (x->parent->left == y) {
              x->parent->left = x;
          }
          else {
              x->parent->right = x;
          }
      }
      else {
          m_root = x;
      }
      y->parent = x;
      if (T2 != NULL) {
          T2->parent = y;
      }
  }
  

  When the line x->parent = y->parent; is executed, the node *y is replaced by *(y->parent). How can I fix this and why does it happen? I'm new with C++, I want to understand pointers.
• when i forgot to delete the pointer then what type of error occur?

  suppose that you write a c program in which you declare a pointer to dynamically allocate memory to store the ages of 10 students. but you forget to delete the pointer. in doing so, what type of bug will occur in the program?
• C: It is possible to pass variables to a function that request a struct so when the function is called these variables are wrapped into a struct?

  I have a function that request a struct.

  struct test{
      const int a;
      const int b;
  };
  
  void testFunction(struct test mytest)
  {
      //code
  }
  

  I was wondering if there is a way of passing two ints to the function so the process of calling it wraps those two ints into a struct.

  Something like:

  void main()
  {
      //function call with some sort of wrapping system...
      testFunction({1,2});
  }
  

  Is there a way to the {1,2} wrapping part?

  (If there is... Could be also done with functions that request pointer to structs?)

  Thanks in advance,

  Juan
• INFO: [CompressingFilter/1.7.1] CompressingFilter has initialized

  "INFO: [CompressingFilter/1.7.1] CompressingFilter has initialized"

  This is my last message shown in the conso le. My Tomcat stuck in this stage. Please give me solution proper solution?