Change content/line of text in a File

[dutchman]

Hello, I want to change a line of text/content in a text file. There are many options, like copy the entire content of the file to a temporary file, seek the content you want and then delete it, put another content in it, close the temporary file and copy everything back. But is there not a easier way to do this?

Here is the entire code

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <windows.h>


    FILE *ofp,*ifp;
    char bnaam[255];


typedef struct {
        char fname['\n'];
        char insertion['\n'];
        char surname['\n'];
        } Name;

typedef struct {
        int number;
        char Character['\n'];
        } Zipcode;

typedef struct  {
        char streetname['\n'];
        int housenum;
        Zipcode zipcode;
        char residence[50];
        } Address;

typedef struct {
        Name name;
        Address address;
        } PD;
        
/* Function for reading the Personal data, scan it and then put it in a file*/

 PD read_PD(void)
{
        PD pd;
      
       printf("Give firstname\n");
       scanf("%s",&PD.name.firstname);
       fprintf(ofp,"%s\n",PD.name.firstname);
       
       printf("Give insertion\n");
       scanf("%s",&PD.name.insertion);
       fprintf(ofp,"%s\n",PD.name.insertion);
       
       printf("Give surname\n");
       scanf("%s",&PD.name.surname);
       fprintf(ofp,"%s\n",PD.name.surname);
       
       printf("Give streetname\n");
       scanf("%s",&PD.address.streetname);
       fprintf(ofp,"%s\n",PD.address.streetname);
       
       printf("Give housenumber\n");
       scanf("%d",&PD.address.housenum);
       fprintf(ofp,"%d\n",PD.address.housenum);
 
       printf("Give zipcode\n");
       scanf("%d%s",&PD.address.zipcode.number,&PD.address.zipcode.character);
       fprintf(ofp,"%d%s\n",PD.address.zipcode.number,&PD.address.zipcode.character);
       
       printf("Give residence\n");
       scanf("%s",&PD.address.residence);
       fprintf(ofp,"%s\n",PD.address.residence);
       
 return pd;
}

/* Function append*/


int append(void)
{
 PD record;
 
if((ofp=fopen(bnaam,"a+"))==NULL)
{
                                 printf("File %s can't be openend for appending",bnaam);
                                 return 0;
                                 }
                                 
record=read_PD();
fclose(ofp);
printf("\nRecord appended\n");
Sleep(1000);
printf("\n");
}

/* END of function append*/

/* Begin function change*/

int change(void)
{
    PD pd;
    int x;
    
    if((ofp=fopen(bnaam,"r+"))==NULL)
{
                                 printf("File %s can't be openend for changing",bnaam);
                                 return 0;
                                 }
                                 
               printf("What do u want to change?\n");
               printf("[1] first name\n");
               printf("[2] insertion\n");
               printf("[3] surname?\n");
               printf("[4] Streetname\n");
               printf("[5] Housenumber\n");
               printf("[6] Zipcode\n");
               printf("[7] Residence\n");
               printf("enter:\t");
               scanf("%d",&x);
               
    switch(x)
    {
             case 1: 
               printf("Give firstname\n");
               scanf("%s",&PD.name.firstname);
               fprintf(ofp,"%s\n",PD.name.firstname);
                  break; 
             case 2: 
              printf("Give insertion\n");
              scanf("%s",&PD.name.insertion);
              fprintf(ofp,"%s\n",PD.name.insertion);
              break;
       
             case 3: 
       printf("Give surname\n");
       scanf("%s",&PD.name.surname);
       fprintf(ofp,"%s\n",PD.name.surname);
                  break; 
             case 4: 
       printf("Give streetname\n");
       scanf("%s",&PD.address.streetname);
       fprintf(ofp,"%s\n",PD.address.streetname);
                  break; 
             case 5: 
      printf("Give housenumber\n");
       scanf("%d",&PD.address.housenum);
       fprintf(ofp,"%d\n",PD.address.housenum);
                  break; 
             case 6: 
       printf("Give zipcode\n");
       scanf("%d%s",&PD.address.zipcode.number,&PD.address.zipcode.character);     fprintf(ofp,"%d%s\n",PD.address.zipcode.number,&PD.address.zipcode.character);
                  break; 
             case 7: 
       printf("Give residence\n");
       scanf("%s",&PD.address.residence);
       fprintf(ofp,"%s\n",PD.address.residence);
                  break; 
             
   }
                  fclose(ofp);
                  printf("\nRecord changed!\n");
                  Sleep(1000);
                  printf("\n");
                  system("cls");
}

int main()
{
    int y;
    int a,b,c,d,e,f;
    char ch;
    
    ifp = fopen("myfile.txt","r");
    ifp == ofp;

    printf("Do you want to use a default file(A) or create one(B)(A/B)?");
    printf("Do you want to close the program (E)?\t");
    printf("\nEnter:\t");
    y=getchar();
    y=toupper(y);
    fflush(stdin);
    system("cls");
    
  if(y=='A'||y=='a'){
                       printf("Enter the file name:\t"); 
                       gets(bnaam);
                       
                       ofp = fopen (bnaam, "r");
                       if(ofp == NULL)
                                       {
                                            printf("Wrong file name\n");
                                            printf("The program is now closing");
                                            Sleep(4000);
                                            return 0;
                                     }
   else{
                  printf("The default file has been openend\n");
                  
       }
       fclose(ofp);
                          } 
     
    
   if(y=='b'||y=='B') {
         printf("Enter the file name you want to create:\t"); 
         scanf("%s",bnaam);
         ofp=fopen(bnaam,"r");
         }
         
    if(y=='E'){
               return 0;
               }
               
    fclose(ofp);           
    
    fflush(stdin);
  
    do {
        
    printf("Welcome at the menu\n\n");
    printf("What do you want to do:\n");
    printf("\n1.\tAppend records?(1)\n");
    printf("2.\tChange Records?(2)\n");
    printf("3.\tShow records?(3)\n");
    printf("4.\tMake a new file?(4)\n");
    printf("5.\tClose program?(5)\n");
    printf("Fill in:\t");
   
   while((y=getchar()) !='\n'){
   
   if(y=='1'){
                  fflush(stdin);
                  system("cls");
                  append();
                  system("cls");
               }
               
   if(y=='2'){
               fflush(stdin);
               system("cls");
               erase();
               }
               
               
   if(y=='3'){
   
              printf("Give the file name that has to be openend\n");
              scanf("%s",bnaam);
 system("cls");
 
 ofp = fopen (bnaam, "r"); 
 
 if (ofp == NULL)
 {
  printf("Can't open the file\n");
  return 0;
 }
 
 ch = fgetc(ofp);
 
 while (ch != EOF)
 {
  printf ("%c", ch);
  ch = fgetc(ofp);
 }
printf("\n\n");
               }
 fclose(ofp);
 
   if(y=='4'){
         printf("Give the name of the file:\t"); 
         scanf("%s",bnaam);
         ofp=fopen(bnaam,"w+");
         fflush(stdin);
         system("cls");
         printf("The new file has been created\n");
         printf("Press enter:");
               }
   if(y=='5'){
               return 0;
               }
   
                                   }
                } 
                while(y !='E');                   
                
    getchar();
    getchar();
    
    fclose(ofp);
    fclose(ifp);
}

NOTE: I am dutch so if there are words in the code that you don't understand, then it's probarly dutch and I didn't change it to English.
Also the text formatting of the code is completely gone, but that's not my fault.
Thanks

[cire]

typedef struct {
        char fname['\n'];
        char insertion['\n'];
        char surname['\n'];
        } Name;

I'm curious what you think this is doing.

Hello, I want to change a line of text/content in a text file. There are many options, like copy the entire content of the file to a temporary file, seek the content you want and then delete it, put another content in it, close the temporary file and copy everything back. But is there not a easier way to do this?

The method you describe is not workable. You have the same problem updating the temporary file as you do with the original file. The usual method to make changes is to read in all of the file data, make any changes to the data and write all of the data back to the file.

This can be accomplished in several ways, the simplest (and least safe is to:)

* Open the data file
* Read the data in
* Close the data file
* Make changes to data
* Reopen the file for output, truncating the file
* Write all of the data back to the file
* Close the file

This can be avoided if the data to be replaced is exactly the same length as the data it is being replaced with. There are ways around this, of course, but they're likely to be overkill for your use case -- you'd be much better off using a database of some sort rather than reinventing one.