C function that counts lines in file

Question

When I try to run my program  I get the wrong number of lines printed   LINES  0   This is the output although I have five lines in my  txt file  Here is my program    include lt stdio h gt   include lt stdlib h gt   int countlines char  filename    void main int argc  char  argv        printf  LINES   d n  countlines argv 1                  int countlines char  filename         count the number of lines in the file called filename                                       FILE  fp   fopen filename  r      int ch 0    int lines 0     if  fp    NULL     return 0     lines      while   ch   fgetc fp      EOF              if  ch      n       lines            fclose fp     return lines      I am sure it is a simple mistake but I am new to programming  Any help would be greatly appreciated

User · Answer

You declare  int countlines char  filename    to take a char   argument   You call it like this  countlines fp    passing in a FILE     That is why you get that compile error   You probably should change that second line to  countlines  Test txt     since you open the file in countlines  Your current code is attempting to open the file in two different places

User · Answer

Here is complete implementation in C C     include  lt stdio h gt   void lineCount int argc char   argv            if argc  lt  2                fprintf stderr  File required                 return                    FILE  fp   fopen argv 1   r               if  fp               fprintf stderr  Error in opening file                return                            int count   1    if a file open  be it empty  it has atleast a newline char         char temp           while fscanf fp   c   amp temp     -1                   if temp    10  count                       fprintf stdout  File has  d lines n  count         int main int argc char   argv            lineCount argc argv           return 0    https   github com KotoJallow Line-Count blob master lineCount c

User · Answer

I don t see anything immediately obvious as to what would cause a segmentation fault  My only suspicion is that your code expects to get a filename as a parameter when you run it  but if you don t pass it  it will attempt to reference one  anyway   Accessing argv 1  when it doesn t exist would cause a segmentation fault  It s generally good practice to check the number of arguments before trying to reference them  You can do this by using the following function prototype for main    and checking that argc is greater than 1  simply  it will indicate the number entries in argv    int main int argc  char   argv    The best way to figure out what causes a segfault in general is to use a debugger  If you re in Visual Studio  put a breakpoint at the top of your main function and then choose Run with debugging instead of  Run without debugging  when you start the program  It will stop execution at the top  and let you step line-by-line until you see a problem   If you re in Linux  you can just grab the core file  it will have  core  in the name  and load that with gdb  GNU Debugger   It can give you a stack dump which will point you straight to the line that caused the segmentation fault to occur   EDIT  I see you changed your question and code  So this answer probably isn t useful anymore  but I ll leave it as it s good advice anyway  and see if I can address the modified question  shortly

User · Answer

while  feof fp       ch   fgetc fp     if ch      n           lines            But please note  Why is    while    feof  file       always wrong

User · Answer

Here is my function   char  fileName    input-1 txt   countOfLinesFromFile fileName    void countOfLinesFromFile char  filename   FILE  myfile   fopen filename   r    int ch  number of lines   0  do       ch   fgetc myfile       if ch      n           number of lines      while  ch    EOF   if ch      n   amp  amp  number of lines    0      number of lines    fclose myfile   printf  number of lines in   s      d  filename  number of lines

User · Answer

You have a   at the end of the if  Change     if  fp    NULL     return 0    to     if  fp    NULL       return 0

User · Answer

You re opening a file  then passing the file pointer to a function that only wants a file name to open the file itself  You can simplify your call to   void main void      printf  LINES   d n  countlines  Test txt         EDIT  You re changing the question around so it s very hard to answer  at first you got your change to main   wrong  you forgot that the first parameter is argc  so it crashed  Now you have the problem of   if  fp    NULL         lt -- note the extra semicolon that is the only thing                            that runs conditionally on the if    return 0            Always runs and returns 0   which will always return 0  Remove that extra semicolon  and you should get a reasonable count

[c] C function that counts lines in file

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