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Q&A How can I modify the code above to accept string as user input and use strcmp to compare with the contents of the text file & then delete that line?

I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string. How can I modify the code below, since the code below take...

1 answer · posted 3y ago by dumplings‭ · edited 2y ago by Alexei‭

Question c file-handling

#5: Post edited by

Alexei‭ · 2022-06-26T16:36:27Z (over 2 years ago)
rollback to previous version

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I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string.
How can I modify the code below, since the code below takes line number as input to delete a specific line.
Thank you.
```
#include <stdio.h>
int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);

I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string.
How can I modify the code below, since the code below takes line number as input to delete a specific line.
Thank you.
```
#include <stdio.h>
int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);
printf(" \n Enter line number of the line to be deleted:");
scanf("%d", &delete_line);
//open new file in write mode
fileptr2 = fopen("replica.c", "w");
ch = 'A';
while (ch != EOF)
{
ch = getc(fileptr1);
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file replica.c
putc(ch, fileptr2);
}
if (ch == '\n')
{
temp++;
}
}
fclose(fileptr1);
fclose(fileptr2);
remove(filename);
//rename the file replica.c to original name
rename("replica.c", filename);
printf("\n The contents of file after being modified are as follows:\n");
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
fclose(fileptr1);
return 0;
}
```
**Example of contents in text file:**
hello world up
one two three
**User input:** hello
**Updated contents in text file:**
one two three

#4: Post edited by

dumplings‭ · 2022-06-26T14:23:11Z (over 2 years ago)

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I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string.
How can I modify the code below, since the code below takes line number as input to delete a specific line.
Thank you.
```
#include <stdio.h>
int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);
~~printf(" \n Enter line number of the line to be deleted:");~~
~~scanf("%d", &delete_line);~~
~~//open new file in write mode~~
~~fileptr2 = fopen("replica.c", "w");~~
~~ch = 'A';~~
~~while (ch != EOF)~~
{
~~ch = getc(fileptr1);~~
~~//except the line to be deleted~~
~~if (temp != delete_line)~~
{
~~//copy all lines in file replica.c~~
~~putc(ch, fileptr2);~~
}
~~if (ch == '\n')~~
{
~~temp++;~~
}
}
~~fclose(fileptr1);~~
~~fclose(fileptr2);~~
~~remove(filename);~~
~~//rename the file replica.c to original name~~
~~rename("replica.c", filename);~~
~~printf("\n The contents of file after being modified are as follows:\n");~~
~~fileptr1 = fopen(filename, "r");~~
~~ch = getc(fileptr1);~~
~~while (ch != EOF)~~
{
~~printf("%c", ch);~~
~~ch = getc(fileptr1);~~
}
~~fclose(fileptr1);~~
~~return 0;~~
}
~~```~~
~~**Example of contents in text file:**~~
~~hello world up~~
~~one two three~~
**User input:** hello
~~**Updated contents in text file:**~~
~~one two three~~

I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string.
How can I modify the code below, since the code below takes line number as input to delete a specific line.
Thank you.
```
#include <stdio.h>
int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);

#3: Post edited by

Alexei‭ · 2021-12-18T16:21:26Z (almost 3 years ago)
minor fixes, removed the fluff

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**Hey I have a question, if lets say I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string... How can I modify the code below, since the code below takes line number as input to delete a specific line. Thank you..**
~~```#include <stdio.h>~~
~~int main()~~
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
~~while (ch != EOF)~~
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);
printf(" \n Enter line number of the line to be deleted:");
scanf("%d", &delete_line);
//open new file in write mode
fileptr2 = fopen("replica.c", "w");
ch = 'A';
while (ch != EOF)
{
ch = getc(fileptr1);
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file replica.c
putc(ch, fileptr2);
}
if (ch == '\n')
{
temp++;
}
}
fclose(fileptr1);
fclose(fileptr2);
remove(filename);
//rename the file replica.c to original name
rename("replica.c", filename);
printf("\n The contents of file after being modified are as follows:\n");
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
fclose(fileptr1);
return 0;
~~}```~~
~~Example of contents in text file:~~
hello world up
one two three
~~User input: hello~~
~~Updated contents in text file:~~
one two three

I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string.
How can I modify the code below, since the code below takes line number as input to delete a specific line.
Thank you.
```
#include <stdio.h>
int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);
printf(" \n Enter line number of the line to be deleted:");
scanf("%d", &delete_line);
//open new file in write mode
fileptr2 = fopen("replica.c", "w");
ch = 'A';
while (ch != EOF)
{
ch = getc(fileptr1);
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file replica.c
putc(ch, fileptr2);
}
if (ch == '\n')
{
temp++;
}
}
fclose(fileptr1);
fclose(fileptr2);
remove(filename);
//rename the file replica.c to original name
rename("replica.c", filename);
printf("\n The contents of file after being modified are as follows:\n");
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
fclose(fileptr1);
return 0;
}
```
**Example of contents in text file:**
hello world up
one two three
**User input:** hello
**Updated contents in text file:**
one two three

#2: Post edited by

dumplings‭ · 2021-12-18T15:17:06Z (almost 3 years ago)

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> **Hey I have a question, if lets say I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string... How can I modify the code below, since the code below takes line number as input to delete a specific line. Thank you..**
```#include <stdio.h>
int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);
printf(" \n Enter line number of the line to be deleted:");
scanf("%d", &delete_line);
//open new file in write mode
fileptr2 = fopen("replica.c", "w");
ch = 'A';
while (ch != EOF)
{
ch = getc(fileptr1);
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file replica.c
putc(ch, fileptr2);
}
if (ch == '\n')
{
temp++;
}
}
fclose(fileptr1);
fclose(fileptr2);
remove(filename);
//rename the file replica.c to original name
rename("replica.c", filename);
printf("\n The contents of file after being modified are as follows:\n");
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
fclose(fileptr1);
return 0;
}```
Example of contents in text file:
hello world up
one two three
User input: hello
Updated contents in text file:
one two three

**Hey I have a question, if lets say I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string... How can I modify the code below, since the code below takes line number as input to delete a specific line. Thank you..**
```#include <stdio.h>
int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;
printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);
printf(" \n Enter line number of the line to be deleted:");
scanf("%d", &delete_line);
//open new file in write mode
fileptr2 = fopen("replica.c", "w");
ch = 'A';
while (ch != EOF)
{
ch = getc(fileptr1);
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file replica.c
putc(ch, fileptr2);
}
if (ch == '\n')
{
temp++;
}
}
fclose(fileptr1);
fclose(fileptr2);
remove(filename);
//rename the file replica.c to original name
rename("replica.c", filename);
printf("\n The contents of file after being modified are as follows:\n");
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
fclose(fileptr1);
return 0;
}```
Example of contents in text file:
hello world up
one two three
User input: hello
Updated contents in text file:
one two three

#1: Initial revision by

dumplings‭ · 2021-12-18T13:57:43Z (almost 3 years ago)

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How can I modify the code above to accept string as user input and use strcmp to compare with the contents of the text file & then delete that line?

 > **Hey I have a question, if lets say I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string... How can I modify the code below, since the code below takes line number as input to delete a specific line. Thank you..**

```#include <stdio.h>
    
    int main()
    {
    FILE *fileptr1, *fileptr2;
    char filename[40];
    char ch;
    int delete_line, temp = 1;

    printf("Enter file name: ");
    scanf("%s", filename);
    //open file in read mode
    fileptr1 = fopen(filename, "r");
    ch = getc(fileptr1);
   while (ch != EOF)
    {
        printf("%c", ch);
        ch = getc(fileptr1);
    }
    //rewind
    rewind(fileptr1);
    printf(" \n Enter line number of the line to be deleted:");
    scanf("%d", &delete_line);
    //open new file in write mode
    fileptr2 = fopen("replica.c", "w");
    ch = 'A';
    while (ch != EOF)
    {
        ch = getc(fileptr1);
        //except the line to be deleted
        if (temp != delete_line)
        {
            //copy all lines in file replica.c
            putc(ch, fileptr2);
        }
        if (ch == '\n')
        {
            temp++;
        }
    }
    fclose(fileptr1);
    fclose(fileptr2);
    remove(filename);
    //rename the file replica.c to original name
    rename("replica.c", filename);
    printf("\n The contents of file after being modified are as follows:\n");
    fileptr1 = fopen(filename, "r");
    ch = getc(fileptr1);
    while (ch != EOF)
    {
        printf("%c", ch);
        ch = getc(fileptr1);
    }
    fclose(fileptr1);
    return 0;
}```




Example of contents in text file:
hello world up
one two three

User input: hello

Updated contents in text file:
one two three

c file-handling

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