I am trying to read a text file, character by character, with fgetc() function but it does not show any output. It is a school project and it is still in very very simple way just to test the functionality of the program.
#include <stdio.h>
#include <stdlib.h>
void fn1(FILE *f);
void fn9(FILE *fp, char, char);
int main() {
FILE *fp = fopen("text.txt", "r");
if (fp == NULL) {
perror("Error: ");
exit(1);
}
fn1(fp);
fn9(fp, '0', '9');
fclose(fp);
return 0;
}
void fn1(FILE *f) {
int num, sum = 0, count = 0;
while (fscanf(f, "%d", &num) == 1) {
if (num > 0) {
sum += num;
count++;
}
}
printf("the avg of positive nums is %.2f", (float) sum / count);
}
void fn9(FILE *fp, char m, char n) {
int ch;
int count1 = 0, count2 = 0;
while ((ch = fgetc(fp)) != EOF) {
if (ch == m)
count1++;
if (ch == n)
count2++;
printf("%c", ch);
if (ferror(fp))
break;
}
printf("\n%c is seen %d times", m, count1);
printf("\n%c is seen %d times", n, count2);
fclose(fp);
}
The file's content that I test is:
90
16
-34
100
After fn(fp) return, fp will point to the last location in the file. It needs to be reset to the start of file before fn9 is called. Use fseek to point fp to the start of file and it should work :)
Related
I read from txt pairs of numbers
How check it only 2 numbers in each line and not 3. I want show the line is the problem for example the pairs file:
3
25 35
14 42
30 60 70
Console: illegal input at line 4
I know That's not the correct way at all. Need use fgets to read and sscanf to parse.
I tried but the memory full garbage. How can I change it correctly?
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
int i, c;
FILE *fp;
char str[100];
fp = fopen("./pairs.txt", "r");
if (dup2(fileno(fp), STDIN_FILENO < 0))
{
printf("Error opening file");
return -1;
}
if (feof(fp))
printf("Error reading file");
scanf("%d", &numOfPairs);
arrNum = (int *)malloc(sizeof(int) * numOfPairs * numbersInPair);
for (int i = 0; i < numOfPairs * numbersInPair; i += 2)
{
int num1, num2;
scanf("%d %d", &num1, &num2);
arrNum[i] = num1;
arrNum[i + 1] = num2;
}
}
Another try NOT working:
int main(int argc, char *argv[])
{
int index, i, numOfPairs;
int c;
FILE *file;
file = fopen("./pairs.txt", "r");
if ((c = getc(file)) == EOF)
{
perror("Error opening file"); //or return 1;
fclose(file);
}
while ((c = getc(file)) != EOF)
putchar(c);
{
fscanf(file, "%d", &numOfPairs);
allNumbers = (int *)malloc(sizeof(int) * numOfPairs * numbersInPair); //need multiply in 2 numbers for each pair
while (!feof(file) && numOfPairs > 0)
{
int x, y, arrIndex = 0;
numOfPairs--;
fscanf(file, "%d %d", &x, &y);
allNumbers[arrIndex] = x;
printf("The X : %d\n", x);
allNumbers[arrIndex + 1] = y;
printf("THE Y : %d\n", y);
arrIndex + 2;
}
fclose(file);
}
Program takes an input file through the command line and outputs the occurrence of each letter in the text file. Not sure where I went wrong.
int main(int argc, char *argv[]) {
char word[1000];
int a = 0;
int b = 0;
int d = 0;
int c = 0;
int e = 0;
int f = 0;
int g = 0;
int h = 0;
int i = 0;
int j = 0;
int k = 0;
int l = 0;
int m = 0;
int n = 0;
int o = 0;
int p = 0;
int q = 0;
int r = 0;
int s = 0;
int t = 0;
int u = 0;
int v = 0;
int w = 0;
int x = 0;
int y = 0;
int z = 0;
int other = 0;
int counter, lenght;
FILE *fp = fopen(argv[1], "r");
fgets(word, 999, fp);
lenght = 1000;
for(counter = 0; counter < lenght; counter++) {
word[counter] = tolower(word[counter]);
if (word[counter] == 'a') {
a++;
}
else if (word[counter] == 'b') {
b++;
}
else if (word[counter] == 'c') {
c++;
}
else if (word[counter] == 'd') {
d++;
}
else if (word[counter] == 'e') {
e++;
}
else if (word[counter] == 'f') {
f++;
}
else if (word[counter] == 'g') {
g++;
}
else if (word[counter] == 'h') {
h++;
}
else if (word[counter] == 'i') {
i++;
}
else if (word[counter] == 'j') {
j++;
}
else if (word[counter] == 'k') {
k++;
}
else if (word[counter] == 'l') {
l++;
}
else if (word[counter] == 'm') {
m++;
}
else if (word[counter] == 'n') {
n++;
}
else if (word[counter] == 'o') {
o++;
}
else if (word[counter] == 'p') {
p++;
}
else if (word[counter] == 'q') {
q++;
}
else if (word[counter] == 'r') {
r++;
}
else if (word[counter] == 's') {
s++;
}
else if (word[counter] == 't') {
t++;
}
else if (word[counter] == 'u') {
u++;
}
else if (word[counter] == 'v') {
v++;
}
else if (word[counter] == 'w') {
w++;
}
else if (word[counter] == 'x') {
x++;
}
else if (word[counter] == 'y') {
y++;
}
else if (word[counter] == 'z') {
z++;
}
else {
other++;
}
}
printf("\nCharacter frequency in %s", argv[1]);
printf("\nCharacter Count");
printf("\na \t\t %d", a);
printf("\nb \t\t %d", b);
printf("\nc \t\t %d", c);
printf("\nd \t\t %d", d);
printf("\ne \t\t %d", e);
printf("\nf \t\t %d", f);
printf("\ng \t\t %d", g);
printf("\nh \t\t %d", h);
printf("\ni \t\t %d", i);
printf("\nj \t\t %d", j);
printf("\nk \t\t %d", k);
printf("\nl \t\t %d", l);
printf("\nm \t\t %d", m);
printf("\nn \t\t %d", n);
printf("\no \t\t %d", o);
printf("\np \t\t %d", p);
printf("\nq \t\t %d", q);
printf("\nr \t\t %d", r);
printf("\ns \t\t %d", s);
printf("\nt \t\t %d", t);
printf("\nu \t\t %d", u);
printf("\nv \t\t %d", v);
printf("\nw \t\t %d", w);
printf("\nx \t\t %d", x);
printf("\ny \t\t %d", y);
printf("\nz \t\t %d", z);
fclose(fp);
return 0;
}
Should output in two columns one being the letter and the next being the number of times that letter occurs
There are problems in your code:
you do not include <stdio.h> nor <ctype.h>
you only read one line and you do not even check if that succeeds. You should write a loop like while (fgets(word, sizeof word, fp)) {
you check all characters in the word array: you should stop at the end of the line: lenght = strlen(word);
tolower() should not be given a char argument, because on platforms where char is signed, negative values invoke undefined behavior. You can cast the argument as (unsigned char) to avoid this: word[counter] = tolower((unsigned char)word[counter]);
More room for improvement:
lenght is misspelt, it should be length.
you should use an array of counters to avoid all these tests and all these explicit printf statements.
check the argument count and fopen() success
no need to read line by line, handle one byte at a time read with getc(). However, reading one large chunk at a time can be faster because it uses fewer tests and locks.
the printf statements should output the newline at the end rather than at the beginning.
Here is a corrected and simplified version:
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
int main(int argc, char *argv[]) {
int count[UCHAR_MAX + 1] = { 0 };
int other, total;
int c;
const char *s;
FILE *fp;
if (argc <= 1) {
fprintf(stderr, "missing input file\n");
return 1;
}
fp = fopen(argv[1], "r");
if (fp == NULL) {
fprintf(stderr, "cannot open input file %s\n", argv[1]);
return 1;
}
total = 0;
while ((c = getc(fp)) != EOF) {
count[tolower(c)] += 1;
total++;
}
printf("Character frequency in %s\n", argv[1]);
printf("Character Count\n");
other = total;
for (s = "abcdefghijklmnopqrstuvwxyz"; *s; s++) {
printf("%c:\t%9d\n", *s, count[(unsigned char)*s]);
other -= count[(unsigned char)*s];
}
printf("other:\t%9d\n", other);
fclose(fp);
return 0;
}
Reading the file by chunks instead of one byte at a time improves the speed dramatically with recent C libraries, because the support for multithreading has made the getc() macros inefficient. Using 64K buffers, the code below is fifty times faster (50X) for a 400MB file:
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#define BUFFER_SIZE 65536
int main(int argc, char *argv[]) {
unsigned char buffer[BUFFER_SIZE];
long count[UCHAR_MAX + 1] = { 0 };
long other;
size_t i, n;
const char *s;
FILE *fp;
if (argc <= 1) {
fprintf(stderr, "missing input file\n");
return 1;
}
fp = fopen(argv[1], "r");
if (fp == NULL) {
fprintf(stderr, "cannot open input file %s\n", argv[1]);
return 1;
}
while ((n = fread(buffer, 1, sizeof buffer, fp)) != 0) {
for (i = 0; i < n; i++) {
count[buffer[i]] += 1;
}
}
other = 0;
for (i = 0; i <= UCHAR_MAX; i++) {
if (isupper(i)) {
count[tolower(i)] += count[i];
} else {
if (!islower(i))
other += count[i];
}
}
printf("Character frequency in %s\n", argv[1]);
printf("Character Count\n");
for (s = "abcdefghijklmnopqrstuvwxyz"; *s; s++) {
printf("%c:\t%9ld\n", *s, count[(unsigned char)*s]);
}
printf("other:\t%9ld\n", other);
fclose(fp);
return 0;
}
Here's a quick implementation I wrote. It doesn't use fgets, but that is most definitely an option.
The flow of the program should be simple, but it is as follows:
Check for a proper argument count.
Declare the variables we'll need.
Declare the file pointer and attempt to open the file.
If the file doesn't open, we'll error out.
Read in every character from the file one at a time and store it into our variable c.
Using our ascii table, we'll alter the values to get them into the proper position in our array.
Print out all of our values.
Close the file.
#include <stdio.h>
int main(int argc, char **argv){
if (argc < 2){
printf("Not enough arguments!\n");
return -1;
}
int A[27] = {0}, c;
FILE *inFile = fopen(argv[1], "r");
if (inFile == NULL){
printf("The file \"%s\" could not be opened.\n", argv[1]);
return -2;
}
while((c = fgetc(inFile)) != EOF){
if ( c >= 'a' && c <= 'z' ){
/* C is a lowercase character */
c-='a';
A[c]++;
}
else if ( c >= 'A' && c <= 'Z' ){
/* C is an uppercase character */
c-='A';
A[c]++;
}
else if (c == '\n'){
/* we're not counting newlines */
continue;
}
else {
A[26]++;
}
}
/* Print out all the values except the "Other" count. */
for (c = 0; c < sizeof A / sizeof A[0] - 1; c++){
printf("%c: %d\n", c+'a', A[c]);
} printf("Other: %d\n", A[26]); //Print out "Other" count
/* Close our file */
fclose(inFile);
return 0;
}
Totals different for same file when executed.
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define MAX_FILE_NAME 100
#define RUNS 1
int main() {
int num,i;
FILE *fp;
char*s, buf[1024];
int count =0;
char c;
char filename[MAX_FILE_NAME];
printf("Enter filename: ");
scanf ("%s",filename);
if ((fp =fopen(filename, "r")) == NULL) {
printf("Error");
exit(1);
}
fscanf(fp,"%d",&num);
for (c = getc(fp); c!= EOF; c = getc(fp))
{
if (c == '\n'){
count = count+1;
}
}
printf("%s has %d numbers \n", filename, count);
int f;
printf("Choose from the options how many processes you want to use [1,2,4]: ");
scanf("%i", &f);
printf("%i processes \n", f);
int fds[f+1][2];
int numb[count];
int x,k;
time_t start, finish;
start = time(NULL);
for(i = 0; i < RUNS; i++)
{
pipe(fds[f]);
for( x = 0; x<f; x++)
{
pipe(fds[x]);
int ind[2];
ind[0] = ((x)*(count/f));
ind[1] = ((x+1)*(count/f));
write(fds[x][1], &ind, 2* sizeof(int));
if (fork() ==0)
{
int t =0;
int ind2[2];
read(fds[x][0], &ind2, 2*sizeof(int));
for( k = ind2[0]; k<ind2[1]; k++)
{
t += numb[k];
}
write(fds[f][1], &t, sizeof(int));
exit(0);
}
}
int m, tmp, total;
total = 0;
for( m = 0; m < f; m++)
{
for( m = 0; m < f; m++)
{
read(fds[f][0], &tmp, sizeof(int));
sleep(5);
total += tmp;
}
printf("DOne calc \n");
printf("Total: %i \n", total);
}
finish = time(NULL);
float runtime = (float)((finish-start)/RUNS);
printf("runtime: %f \n", runtime);
fclose(fp);
return 0;
}
You get random result for the same input because the calculation based on uninitialized int numb[count]; values.
According to the C99 standard, section 6.7.8.10:
If an object that has automatic storage duration is not initialized explicitly, its value is indeterminate.
Because of it int numb[count]; contains some random junk from memory. To get predictive results use explicit initialization:
#include <string.h> // memset
int numb[count];
memset (numb, 0, sizeof(numb)); // Zero-fills
Use the code bellow to put numbers from filename file into numb:
int i = 0;
char line[1024];
fseek(fp, 0, SEEK_SET);
while(fgets(line, sizeof(line), fp) )
{
if( sscanf(line, "%d", &numb[i]) == 1 ) // One number per line
{
++i;
}
}
Have made a program that reads a .csv file and stores the highest number in another file. The problem is that my program can't read comma separated numbers like 1,5,6,7,1,2. Here is the loop I need help to change
int i;
int max = 0;
int min = 0;
while (!feof(fp))
{
fscanf( fp, "%d", &i);
if (i < min)
min = i;
if (i > max)
max = i;
}
And this is what I print out:
fprintf(q,"%d",max);
printf("maximum value is %d \n", max);
fclose(q);
fclose(fp);
#include <stdio.h>
#include <limits.h>
int main(void){
FILE *fp = fopen("input.csv", "r");
FILE *q = fopen("max.txt" , "w");
int i;
int max = INT_MIN;
int min = INT_MAX;
while(1){
int state = fscanf(fp, "%d", &i);
if(state == 1){
if (i < min)
min = i;
if (i > max)
max = i;
} else if(state == EOF){
break;
} else {
char ch;
fscanf(fp, " %c", &ch);
if(ch != ','){
fprintf(stderr, "\nformat error\n");
break;
}
}
}
fprintf(q, "%d", max);
printf("maximum value is %d\n", max);
fclose(q);
fclose(fp);
return 0;
}
I'm trying to write a program which will read from text files and then output the minimum, maximum and average values. The trouble I am having is ignoring comments in the text files that begin with a hashtag. Here is my working code so far. Can anyone help?
#include <stdio.h>
#include <stdlib.h>
int main( void )
{
char ch, filename[20];
FILE *lun;
int num, min, max, sum, count, first;
printf("Please enter the name of file to load:");
scanf ("%s", filename);
lun=fopen(filename, "r");
if ( lun != NULL)
{
for ( sum= count= first= 0; fscanf( lun, "%d", &num ) == 1; sum += num, ++count )
if ( !first ) { min= max= num; first= 1; }
else if ( num > max ) max= num;
else if ( num < min ) min= num;
fclose( lun );
printf( " Minimum value: %d\n Maximum value: %d\n Average value: %lf\n",
min, max, sum / (double) count );
}
else
printf( "Unable to read file.\n" );
return 0;
}
Read the data in lines (use fgets()).
If the line contains a #, terminate the string there by replacing the '#' with '\0'. Then scan the line for numbers.
See also How to use sscanf() in loops?
And don't forget to check that the file was opened.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void)
{
char filename[20];
printf("Please enter the name of file to load: ");
if (scanf("%19s", filename) != 1)
{
fprintf(stderr, "Failed to read file name\n");
return 1;
}
FILE *lun = fopen(filename, "r");
if (lun == NULL)
{
fprintf(stderr, "Failed to open file %s for reading\n", filename);
return 1;
}
char line[4096];
int min = 0; // Avoid compilation warnings (may be used uninitialized)
int max = 0; // Ditto
int sum = 0;
int count = 0;
while (fgets(line, sizeof(line), lun) != NULL)
{
char *hash = strchr(line, '#');
if (hash != NULL)
*hash = '\0';
int pos;
int num;
int off = 0;
while (sscanf(line + off, "%d%n", &num, &pos) == 1)
{
if (count == 0)
min = max = num;
if (num > max)
max = num;
if (num < min)
min = num;
sum += num;
count++;
off += pos; // Skip through line
}
}
fclose(lun);
printf("Minimum value: %d\nMaximum value: %d\nAverage value: %lf\n",
min, max, sum / (double)count);
return 0;
}
If your compiler doesn't support C99 or later, you will have to move variable declarations to the start of a block (immediately after a {).
Handling doubles isn't really any harder:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void)
{
char filename[20];
printf("Please enter the name of file to load: ");
if (scanf("%19s", filename) != 1)
{
fprintf(stderr, "Failed to read file name\n");
return 1;
}
FILE *lun = fopen(filename, "r");
if (lun == NULL)
{
fprintf(stderr, "Failed to open file %s for reading\n", filename);
return 1;
}
char line[4096];
double min = 0.0; // Avoids 'used when uninitialized' warnings
double max = 0.0; // Avoids 'used when uninitialized' warnings
double sum = 0;
int count = 0;
while (fgets(line, sizeof(line), lun) != NULL)
{
char *hash = strchr(line, '#');
if (hash != NULL)
*hash = '\0';
int pos;
double num;
int off = 0;
while (sscanf(line + off, "%lf%n", &num, &pos) == 1)
{
if (count == 0)
min = max = num;
if (num > max)
max = num;
if (num < min)
min = num;
sum += num;
count++;
off += pos; // Skip through line
}
}
fclose(lun);
printf("Minimum value: %f\nMaximum value: %f\nAverage value: %f\n",
min, max, sum / count);
return 0;
}