For input two files "cl-clean-history" and "cd-clean-history" of similar structure of:
"Lift Convergence"
"Iterations" "cl"
1 1.14094e+00
2 1.14094e+00
and
"Drag Convergence"
"Iterations" "cd"
1 0.14094e+00
2 0.14094e+00
I want to write a program to read the values in second columns in both files and compute its divisor.
My program code is:
#include <stdio.h>
#include <errno.h>
int main (void)
{
double max_cl_cd, cl_cd_temp;
int lines_file;
int tab_line;
double tab_scan_file[200000][4];
int ch=0;
FILE *result_search_cl;
FILE *result_search_cd;
max_cl_cd=0.0;
if((result_search_cl=fopen("cl-clean-history","r"))==NULL)
{
printf("Unable to open input file\n");
}
else
{
lines_file = 0;
FILE *result_search_cd = fopen("cd-clean-history", "r");
FILE *result_search_cl = fopen("cl-clean-history", "r");
while (EOF != (ch=getc(result_search_cd)))
if ('\n' == ch)
++lines_file;
printf("Number of lines in file: %d \n",lines_file);
for (tab_line=0;tab_line<=lines_file;tab_line++) {
fscanf(result_search_cd,"\n");
fscanf(result_search_cd,"\n");
fscanf(result_search_cd,"%d",&tab_scan_file[tab_line][0]);
fscanf(result_search_cd,"\t");
fscanf(result_search_cd,"%f",&tab_scan_file[tab_line][1]);
fscanf(result_search_cd,"\n");
fscanf(result_search_cl,"%d",&tab_scan_file[tab_line][2]);
fscanf(result_search_cl,"\t");
fscanf(result_search_cl,"%f",&tab_scan_file[tab_line][3]);
fscanf(result_search_cl,"\n");
cl_cd_temp=tab_scan_file[tab_line][3]/tab_scan_file[tab_line][1];
if (cl_cd_temp>max_cl_cd)
{
max_cl_cd=cl_cd_temp;
}
printf("%f %f\n",tab_scan_file[tab_line][0],tab_scan_file[tab_line][1]);
}
fclose(result_search_cd);
fclose(result_search_cl);
}
printf("%f %f\n",tab_scan_file[tab_line][0],tab_scan_file[tab_line][1]);
return 0;
}
In my opinion there is something bad in scanf lines, but I don't see what exactly is bad. The first two scans of "\n" are intented to jump two first lines in file. I know that the second option is to perform loop starting from third line (for(tab_line=3; etc.) The %d scans integer value in first column and %f scans float value in second column in both files. Unfortunately, while running in Dev C++ the process exits with return value 3221225725. I found on stackoverflow.com that this value means heap corruption. How to overcome this problem?
I think you should read the fscanf documentation again:
Anyway, fscanf accepts as a second argument a format, so something like "%d" (the one you have used some lines later). When you invoke
fscanf(result_search_cd,"\n");
"\n" is not an identifier. You should replace this line with something like
while (getc(result_search_cd) != "\n"); //Skip first line
while (getc(result_search_cd) != "\n"); //Skip second line
Related
I pretty new to C, or well, very new to C. I'm trying to write integers to a file using putw(), and then I try to read them using getw(), I read them using a while loop until EOF. But the loop dies prematurely, and it seems to do so when getw() gets the integer 26 from the file. I'm at a complete loss.
Basically I want to printf the integers that I previously saved to the file, using putw(), every 7th iteration I print a new line. It works all the way until getw() encounters the integer 26, that kills the loop, even if it isnt EOF. No matter how many integers I have in the file, it works only until getw() encounters 26. I´ve tried using fscanf but didnt get that to work either. Please help a beginner.
void readfile() {
FILE *f;
f = fopen("INTEGERS.DAT", "r");
int num, xar=1;
if (f==NULL){
printf("NO file detected.\n");
exit(0);
} else {
while((num = getw(f)) != EOF) {
printf("%d ", num);
if ( xar % 7 == 0) {
printf("\n");
}
xar++;
}
}
fclose(f);
}
Thanks in advance.
You didn't indicate the format of your data file, but noting that you are opening the file with an "r" parameter, that would indicate that the data in the file is in a text format and not a binary format. So using that information and a bit of artistic license, I created a code snippet to build some text data with an integer value per line/record in a file, and then read the data in that file utilizing a tweaked version of your readfile function.
#include <stdio.h>
#include <stdlib.h>
void save_int(void)
{
int entry = 999;
FILE *fp;
fp = fopen("INTEGERS.DAT", "w");
if (fp != NULL)
{
while (1)
{
printf("Enter an integer or enter '0' to quit data entry: ");
scanf("%d", &entry);
if (entry == 0)
{
break;
}
fprintf(fp, "%d\n", entry);
}
}
fclose(fp);
return;
}
void readfile()
{
FILE *fp;
fp = fopen("INTEGERS.DAT", "r");
char number[16];
int value;
if (fp==NULL)
{
printf("NO file detected.\n");
exit(0);
}
else
{
while(1)
{
value = fscanf(fp, "%s", number);
if (value < 0)
{
break;
}
printf("%d ", atoi(number));
}
}
printf("\n");
fclose(fp);
}
int main()
{
save_int();
readfile();
return 0;
}
Some items to point out.
Each integer value is being written with a newline character to the text file, so that would be a caveat if your file actually is in a different format such as storing integers on the same line with some type of delimiter between the integer values.
In reading in the integer data from the created text file, fscanf is used for this task - you might get suggestions and other answers utilizing other functions such as fgets. There are pros and cons, so often it comes down to what is most familiar and comfortable to you.
Since the values were stored as string values, they are read in to a string and then converted to an integer utilizing the standard atoi function. Again, this is just a simple way to do this that I am familiar with. By all means, view any alternative answers you might get and/or comments added later to this answer.
With that, following is some sample output at the terminal.
#Dev:~/C_Programs/Console/Integers/bin/Release$ ./Integers
Enter an integer or enter '0' to quit data entry: 14
Enter an integer or enter '0' to quit data entry: 566
Enter an integer or enter '0' to quit data entry: 65335
Enter an integer or enter '0' to quit data entry: 122
Enter an integer or enter '0' to quit data entry: 18
Enter an integer or enter '0' to quit data entry: 0
14 566 65335 122 18
#Dev:~/C_Programs/Console/Integers/bin/Release$ cat INTEGERS.DAT
14
566
65335
122
18
Go ahead and test this out to see if it meets the spirit of your project.
Write a C program that reads from the keyboard a natural number n
with up to 9 digits and creates the text file data.out containing the
number n and all its non-zero prefixes, in a single line, separated by
a space, in order decreasing in value. Example: for n = 10305 the data
file.out will contain the numbers: 10305 1030 103 10 1.
This is what I made:
#include <stdio.h>
int main()
{
int n;
FILE *fisier;
fisier=fopen("date.in","w");
printf("n= \n");
scanf("%d",&n);
fprintf(fisier,"%d",n);
while(n!=0)
{
fisier=fopen("date.in","r");
n=n/10;
fprintf(fisier,"%d",n);
}
fclose(fisier);
}
Few things:
Function calls may return error. You need to check that every time.
fisier=fopen("date.in","w");
This should have been followed by an error check. To understand more on what it return, first thing you should do is read the man page for that function. See man page for fopen(). If there is an error in opening the file, it will return NULL and errno is set to a value which indicates what error occurred.
if (NULL == fisier)
{
// Error handling code
;
}
Your next requirement is separating the numbers by a space. There isn't one. The following should do it.
fprintf(fisier, "%d ", n);
The next major problem is opening the file in a loop. Its like you are trying to open a door which is already open.
fisier=fopen("date.in","r");
if(NULL == fisier)
{
// Error handling code
;
}
while(n!=0)
{
n=n/10;
fprintf(fisier,"%d",n);
}
fclose(fisier);
A minor issue that you aren't checking is the number is not having more than 9 digits.
if(n > 999999999)
is apt after you get a number. If you want to deal with negative numbers as well, you can modify this condition the way you want.
In a nutshell, at least to start with, the program should be something similar to this:
#include <stdio.h>
// Need a buffer to read the file into it. 64 isn't a magic number.
// To print a 9 digit number followed by a white space and then a 8 digit number..
// and so on, you need little less than 64 bytes.
// I prefer keeping the memory aligned to multiples of 8.
char buffer[64];
int main(void)
{
size_t readBytes = 0;
int n = 0;
printf("\nEnter a number: ");
scanf("%d", &n);
// Open the file
FILE *pFile = fopen("date.in", "w+");
if(NULL == pFile)
{
// Prefer perror() instead of printf() for priting errors
perror("\nError: ");
return 0;
}
while(n != 0)
{
// Append to the file
fprintf(pFile, "%d ", n);
n = n / 10;
}
// Done, close the file
fclose(pFile);
printf("\nPrinting the file: ");
// Open the file
pFile = fopen("date.in", "r");
if(NULL == pFile)
{
// Prefer perror() instead of printf() for priting errors
perror("\nError: ");
return 0;
}
// Read the file
while((readBytes = fread(buffer, 1, sizeof buffer, pFile)) > 0)
{
// Preferably better way to print the contents of the file on stdout!
fwrite(buffer, 1, readBytes, stdout);
}
printf("\nExiting..\n\n");
return 0;
}
Remember: The person reading your code may not be aware of all the requirements, so comments are necessary. Secondly, I understand english to a decent level but I don't know what 'fisier' means. Its recommended to name variables in such a way that its easy to understand the purpose of the variable. For example, pFile is a pointer to a file. p in the variable immediately gives an idea that its a pointer.
Hope this helps!
To draw a conclusion from all the comments:
fopen returns a file handle when successfull and NULL otherwise. Opening a file twice might result in an error (it does on my machine), such that fisier is set to NULL inside the loop. Obvioulsy fprintf to NULL wont do anything.
You only need to call fopen once, so remove it from the loop. After that it will work as intended.
It's alwas good to check if the fopen succeeded or not:
FILE *fisier;
fisier=fopen("date.in","w");
if(!fisier) { /* handle error */ }
You print no spaces between the numbers. Maybe that's intended, but maybe
fprintf(fisier,"%d ",n);
would be better.
I am writing a program that inputs two text files
inputtxt1,
inputtxt2
and output
outputtxt file
In these two files information such as
input txt1
S00111111 5 6-Jul-19 09-Aug-19
S00800000 4 1-Jul-19 30-Aug-19
S00000000 1 1-Jul-19 30-Aug-19
input txt2
S00111111 3 6-Jul-19 09-Aug-19
S00222222 1 20-Jul-19 30-Aug-19
S00000000 1 1-Jul-19 30-Aug-19
I am writing a program to input these two txt files and output the differences in SQL queries and the values inside the bracket will change depends on the differences from these text files.
DELETE FROM TABLE WHERE TABLE=[] AND TABLE=[]
INSERT INTO TABLE (TABLE1,TABLE2,TABLE3,TABLE4) VALUES ([ ],[],'[2019-08-30] 00:00:00','[2019-07-01] 00:00:00');
DELETE FROM TABLE WHERE TABLE=[] AND TABLE=[4]
INSERT INTO TABLE (TABLE,TABLE) VALUES ([],[4]);
I wrote my draft in C so what I did id basically a while loop to read each of the line of the first file and each of the line of the second file and output the query.
Here are my two questions:
First it, unfortunately, output the file SQL 3 times, I think there is something wrong with my while loop.
Secondly, how would I make the program detect that specific character from specific line need to be printed in the query for example number 5 in the first line would detect and add to the value of one of the tables in the query.
/* This program will input two text files, output a text file with the differences*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
FILE *in1, *in2, *out;
int a, b;
void main (void)
{
int c;
char* singleline [33];
char* singleline2 [33];
in1 = fopen ("inputtest1.txt", "r"); /* reads from the first file */
in2 = fopen ("inputtest2.txt", "r"); /* reads from the second file */
out = fopen ("outputtest3", "w"); /* writes out put to this file */
// Menu //
printf ("TSC Support Program\n\n");
printf ("This program compare the two files and output the differences in SQL quries \n");
// if the file is empty or something went wrong!
if (in1 == NULL || in2 == NULL)
{
printf("********************Can Not Read File !**************************");
}
else
{
// Checking Every line in the first text file if it equals to the first line of the text file
while (!feof(in1)&&!feof(in2))
{
// a = getc(in1);
// b = getc(in2);
a = fgets(singleline, 33,in1);
b = fgets(singleline2, 33,in2);
if (a!=b)
{
printf("\n SQL will be printed\n");
fprintf (out,
"\n DELETE FROM BADGELINK WHERE BADGEKEY=[27] AND ACCLVLID=75"
"\nINSERT INTO BADGELINK (BADGEKEY,ACCLVLID,ACTIVATE,DEACTIVATE) VALUES ([27],75,'[2010-08-24] 00:00:00','[2010-12-17] 00:00:00'); \n"
"\n DELETE FROM BADGE WHERE BADGEKEY=[27] AND ISSUECODE=[75]"
"\nINSERT INTO BADGE (BADGEKEY,ISSUECODE) VALUES ([27],[1]);\n"
);
}
else
{
printf("Something went wrong");
}
}
}
fclose(in1);
fclose(in2);
fclose(out);
}
It prints the output 5 times
and then it says something went wrong. I am unsure what went wrong.
if (a != b) does not do what you think it is doing. Check strncmp() or memcmp() library functions.
But if you want to find out the first different character in two strings, the code below would do it for you.
Not tested properly, so take it as a quick prototype.
#include <stdio.h>
int strdiff(char *s1, char *s2){
char *p1 = s1;
while(*s1++ == *s2++)
;
if (s1 != s2)
return --s1-p1; /* we have s1++ in the while loop */
return -1;
}
int main(){
char *s1="S00111111 5 6-Jul-19 09-Aug-19";
char *s2="S00111111 3 6-Jul-19 09-Aug-19";
int i = strdiff(s1,s2);
printf("%d %c\n",i, s1[i]);
return 0;
}
Mind you, comparing two files line by line may turn out to be a bigger mission than it sounds if the two files you are comparing do not have exactly the same lines (with minor differences of course).
I'm fairly new to C. This is the first program I've written involving reading and writing to files. So far, I was able to read the file, perform the operations I need but I am having trouble with 2 things.
Whatever the file is, it omits the last line when reading. For example if the file has:
3
5
6
It will only read the 3 and 5. But if I leave an empty/blank line at the bottom it'll read all three. Any ideas as why that is?
I now need to take what I did, essentially converting volts to milliVolts, microVolts, etc. and write it back to the file. What I have been doing up until now is reading it from the file and working through the console. So essentially, I want write the last two printf statements to the file. I had some attempts at this but it wasn't working and I couldn't seem to find decent support online for this. When I tried, it would completely erase what was in the file before.
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char** argv) {
FILE * file = fopen ("bacon.txt", "r");
float voltage = 0, voltageArray[100], voltageToMilli = 0,voltageToMicro = 0, voltageToKilo = 0, voltageToMega = 0;
int i = 1, j = 0;
fscanf (file, "%f", &voltage);
while (!feof (file)) {
printf("Line # %d\n", i);
printf ("The voltage is: %f\n", voltage);
voltageArray[j] = voltage;
fscanf (file, "%f", &voltage);
printf("The voltage in Element %d is: %f Volts",j,voltageArray[j]);
voltageToMilli = voltageArray[j] * 1000;
voltageToMicro = voltageArray[j] * 1000000;
voltageToKilo = voltageArray[j] * 0.001;
voltageToMega = voltageArray[j] *0.000001;
printf("\nThe voltage is %f Volts, which is: %f milliVolts, %f microVolts, %f kiloVolts, %f megaVolts",voltageArray[j],voltageToMilli,voltageToMicro,voltageToKilo,voltageToMega);
printf("\n\n");
i++;
j++;
}
fclose (file);
return (0);
}
Please try to keep explanations clear and simple as I am a beginner in C. Thank you!
For the first issue, the problem is that the loop logic is incorrect. On each iteration is stores the previous read data, reads the next data and then goes back to the top of the loop. The problem with this is that the next data is not stored until the next iteration. But after reading the last data item (and before storing it into the array) the feof check is always false. Refer to this question for why checking feof as a loop condition is almost always wrong.
Here is an example of how you could restructure your code to read all the items as intended:
int rval;
while ((rval = fscanf(file, "%f", &voltage)) != EOF) {
if (rval != 1) {
printf("Unexpected input\n");
exit(-1);
}
voltageArray[j] = voltage;
/* Do the rest of your processing here. */
}
problem is in the file there is nothing after the last number,
so, after reading the last number from the file, feof(file) is true.
and the while exits.
simplest fix is change it to this
while(fscanf (file, "%f", &voltage) == 1) {
and remove the other fscanf calls.
this works because that fscanf() call will return 1 when it is able
to read a number and either 0 or EOF (which is a negative number)
otherwise.
This is a first formal C competition I am going through .In the last years paper they had- Specified something called aromatic number and told to find those .I wrote the code and it works well but I am not able to understand these instructions about input and output and how to code them in C for Windows.
I am aware about reading one letter from a file and writing it using fopen() and fprintf and fscanf. But these are letters written in different lines how to extract them as variables from in1.dat and print them in out1.dat?
Means I know
int main()
{
int n;
FILE *fptr;
if ((fptr=fopen("D:\\program.dat","r"))==NULL){
printf("Error! opening file");
exit(1); /* Program exits if file pointer returns NULL. */
}
fscanf(fptr,"%d",&n);
printf("Value of n=%d",n+n);
fclose(fptr);
getch();
}
Which scans the first value in the 1st line .But they ask for multiple lines(3 in sample input) how to do them?
fscanf(fptr,"%d",&n);
printf("Value of n=%d",n+n);
Instead do like this -
while(fscanf(fptr,"%d",&n))
{
printf("Value of n=%d",n+n); //But notice here with every iteration n will be over-written.
}
This will stop at the first conversion failure or end of the file.And then inside this loop you can write into output file .
Try Something Like This:
#include<stdio.h>
int main()
{
FILE *in,*out;
int num;
char line[512],aronum[20];
in = fopen("in.dat", "r");
out = fopen("out.dat","w");
fgets(line, 512, in); //to get number of test cases
sscanf (line, "%d",&num);
while((fgets(line, 512, in) != NULL) && (num--))
{
sscanf (line, "%s",&aronum);
fprintf(out,"%d",calc(aronum)); //use `calc` func to return int ans.
}
fclose(in);
fclose(out);
return 0;
}