Write a program to replace one line with another line in a file.
#include<stdio.h>
#include"fileinfo.h"
void Replace_Line_in_File(FILE*,int,char*);
int main()
{
FILE *fptr;
int LinetoReplace;
char fileName[32];
printf("Enter FileName = ");
scanf("%[^\n]",fileName);
fptr = fopen(fileName,"r");
if(fptr == NULL)
{
printf("file does not present in this directory\n");
return 0;
}
printf("Which line do you want to Replace = ");
scanf("%d",&LinetoReplace);
Replace_Line_in_File(fptr,LinetoReplace,fileName);
return 0;
}
void Replace_Line_in_File(FILE* fp,int line,char* file)
{
int LineCount,MaxStrLen,i;
char StringToAdd[100],**cp;
LineCount = Get_Total_Lines(fp);
if(line >= 1 && line <= LineCount)
{
line--;
printf("Enter String to Replace\n");
scanf(" %[^\n]",StringToAdd);
cp = (char**)malloc(sizeof(char*)*LineCount);
MaxStrLen = Get_Max_String_Length(fp);
for(i = 0;i<LineCount;i++)
{
cp[i] = (char*)malloc(MaxStrLen+1);
fgets(cp[i],MaxStrLen+1,fp);
}
fclose(fp);
fp = fopen(file,"w");
for(i = 0;i<LineCount;i++)
{
if(i == line)
{
fputs(StringToAdd,fp);
fputc('\n',fp);
}
else
fputs(cp[i],fp);
}
fclose(fp);
printf("Replacing Done.....\n");
}
else
{
fclose(fp);
printf("Invalid Line Number\n");
}
}
Note: File name d1 is present in the current working directory.
cat d1 Lot To Learn BlackBerry Iphone Incredible India
Output
Enter FileName = d1 Which line do you want to Replace = 2 Enter String to Replace BlackBerry Z10 Repacling Done.....
Lot To Learn BlackBerry Z10 Iphone Incredible India