I have an issue about searching in .txt file. Here is my code:
int Search_in_File(char *fname, char pass[]) {
FILE *fp;
int line_num = 1;
int find_result = 0;
char temp[20];
if((fp = fopen(fname, "r")) == NULL) {
return(-1);
}
while(fgets(temp, 20, fp) != NULL) {
if(strncmp(temp, pass, 6) == 0)
{
printf("A match found on line: %d\n", line_num);
printf("\n%s\n", temp);
find_result++;
}
line_num++;
}
if(find_result == 0) {
printf("\nSorry, couldn't find a match.\n");
}
//Close the file if still open.
if(fp) {
fclose(fp);
}
return(0);
}
int main(void) {
char pass[20];
printf("Enter a password:\n");
scanf("%s", &pass);
Search_in_File("100000.txt", pass);
getchar();
return 0 ;
}
If i use strcmp(), The program cannot find any matches. But if I use strncmp(), I can get the results but I get all passwords which matches the first 6 characters. How can i get exact matches?
Bruteforce approach.
#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int findInFile(FILE *fp, const char *str)
{
void *data;
long flength;
int result = -1;
fseek(fp, 0L, SEEK_END);
flength = ftell(fp);
fseek(fp, 0L, SEEK_SET);
data = malloc(flength);
if(data && fread(data, flength, 1, fp) == flength)
{
result = 0;
char *pos = memmem(data, flength, str, strlen(str));
if(pos)
{
printf("Match at %zu\n", pos - (char *)data);
}
else
{
printf("String not found\n");
}
}
free(data);
fseek(fp, 0L, SEEK_SET);
return result;
}
Related
I need to load strings from file into a struct array.
CORRECT OUTPUT:
4
Sarajevo,345123
Tuzla,123456
Mostar,101010
Banja Luka,234987
MY OUTPUT:
1
Sarajevo 345123
Tuzla 123456
Mostar 101010
Banja Luka 234987,544366964
Code:
#include <stdio.h>
#include <string.h>
struct City {
char name[31];
int number_of_citizen;
};
int load(struct City cities[100], int n) {
FILE *fp = fopen("cities.txt", "r");
int i = 0;
while (fscanf(fp, "%[^,]s %d\n", cities[i].name, &cities[i].number_of_citizen)) {
i++;
if (i == n)break;
if (feof(fp))break;
}
fclose(fp);
return i;
}
int main() {
int i, number_of_cities;
struct City cities[10];
FILE* fp = fopen("cities.txt", "w");
fputs("Sarajevo 345123", fp); fputc(10, fp);
fputs("Tuzla 123456", fp); fputc(10, fp);
fputs("Mostar 101010", fp); fputc(10, fp);
fputs("Banja Luka 234987", fp);
fclose(fp);
number_of_cities = load(cities, 10);
printf("%d\n", number_of_cities);
for (i = 0; i < number_of_cities; i++)
printf("%s,%d\n", cities[i].name, cities[i].number_of_citizen);
return 0;
}
Could you explain me how to fix this? Why my program only loaded 1 city?
The fscanf() conversion string is incorrect: instead of "%[^,]s %d\n" you should use:
while (i < n && fscanf(fp, "%30[^,],%d",
cities[i].name,
&cities[i].number_of_citizen) == 2) {
i++;
}
Or better:
#include <errno.h>
#include <stdio.h>
#include <string.h>
int load(struct City cities[], int n) {
char buf[200];
int i = 0;
char ch[2];
FILE *fp = fopen("cities.txt", "r");
if (fp == NULL) {
fprintf(stderr, "cannot open %s: %s\n", "cities.txt",
strerror(errno));
return -1;
}
while (i < n && fgets(buf, sizeof buf, fp)) {
if (sscanf(buf, "%30[^,],%d%1[\n]",
cities[i].name,
&cities[i].number_of_citizen, ch) == 3) {
i++;
} else {
fprintf(stderr, "invalid record: %s\n", buf);
}
}
fclose(fp);
return i;
}
Also change your main function to output commas between the city names and population counts:
int main() {
int i, number_of_cities;
struct City cities[10];
FILE *fp = fopen("cities.txt", "w");
if (fp) {
fputs("Sarajevo,345123\n", fp);
fputs("Tuzla,123456\n", fp);
fputs("Mostar,101010\n", fp);
fputs("Banja Luka,234987\n", fp);
fclose(fp);
}
number_of_cities = load(cities, 10);
printf("%d\n", number_of_cities);
for (i = 0; i < number_of_cities; i++)
printf("%s,%d\n", cities[i].name, cities[i].number_of_citizen);
return 0;
}
EDIT: since there are no commas in the database file, you must use a different parsing approach:
#include <errno.h>
#include <stdio.h>
#include <string.h>
int load(struct City cities[], int n) {
char buf[200];
int i = 0;
FILE *fp = fopen("cities.txt", "r");
if (fp == NULL) {
fprintf(stderr, "cannot open %s: %s\n", "cities.txt",
strerror(errno));
return -1;
}
while (i < n && fgets(buf, sizeof buf, fp)) {
/* locate the last space */
char *p = strrchr(buf, ' ');
if (p != NULL) {
/* convert it to a comma */
*p = ',';
/* convert the modified line */
if (sscanf(buf, "%30[^,],%d",
cities[i].name,
&cities[i].number_of_citizen) == 2) {
i++;
continue;
}
}
fprintf(stderr, "invalid record: %s", buf);
}
fclose(fp);
return i;
}
What is the best way to read name and its value from a configuration file in c programming?
Sample configuration file:
NAME=xxxx
AGE=44
DOB=mmddyyyy
WORK=zzzz
This is the code which I am using. It is working. But I would like to know if there is a better way.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int getValue(char *line, char* name, char value[])
{
char* pch = NULL;
char* token = NULL;
pch = strstr(line, name);
if(pch)
{
token = strtok(pch, "=");
while (token != NULL)
{
pch = token;
token = strtok(NULL, "=");
}
pch[strcspn ( pch, "\n" )] = '\0';
strcpy(value,pch);
return 1;
}
return 0;
}
int main()
{
FILE * fp;
char * line = NULL;
size_t len = 0;
ssize_t read;
char value[100];
int ret = 0;
fp = fopen("test.txt", "r");
if (fp == NULL)
{
printf ("Cannot open file \n");
return -1;
}
while ((read = getline(&line, &len, fp)) != -1)
{
ret = getValue(line,"NAME",value);
if (ret)
{
printf("NAME is %s\n", value);
}
ret = getValue(line,"AGE",value);
if (ret)
{
printf("AGE is %s\n", value);
}
}
free(line);
fclose(fp);
return 0;
}
I would be also happy to hear if there is any issue with this code.
There are several issues
When the file is like below, your parsing is incorrect. it be found as long as there is this string on the line, regardless of whether it is on the value or part of the key.
NAMEX=xxxx
AGEX=44
DOB=mmddyyyyAGE
WORK=zzzzAGE
Use strtok line content will be changed. In fact, when you call getValue for the second time, the content of line is different from the file.
AGE=NAMEzzzz=1=2
From the performance, you can directly use line the substring, no need to strcpy out
It is recommended to parse the key and value first, then compare the key you are looking for multiple times. the code below is for reference only
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
char *trim(char *str)
{
char *start = str;
char *end = str + strlen(str);
while(*start && isspace(*start))
start++;
while(end > start && isspace(*(end - 1)))
end--;
*end = '\0';
return start;
}
int parse_line(char *line, char **key, char **value)
{
char *ptr = strchr(line, '=');
if (ptr == NULL)
return -1;
*ptr++ = '\0';
*key = trim(line);
*value = trim(ptr);
return 0;
}
int main()
{
FILE *fp;
char *line = NULL;
size_t len = 0;
ssize_t read;
char *key, *value;
fp = fopen("test.txt", "r");
if (fp == NULL) {
printf ("Cannot open file \n");
return -1;
}
while ((read = getline(&line, &len, fp)) != -1) {
if (parse_line(line, &key, &value))
continue;
if (strcmp(key, "NAME") == 0) {
printf("NAME is %s\n", value);
} else if (strcmp(key, "AGE") == 0) {
printf("AGE is %s\n", value);
}
}
free(line);
fclose(fp);
return 0;
}
I must modify my program to accept input from
a file called anagrams.txt.This file should have two strings per line, separated by the # character. My program should read
each pair of strings and report back if each pair of strings is an anagram. For example consider the following content of anagrams.txt:
hello#elloh
man#nam
Astro#Oastrrasd
Your program should print out the following:
hello#elloh - Anagrams!
man#nam - Anagrams!
Astro#Oastrrasd- Not anagrams!
I should compile in g++
Here is the code to read from text:
int main()
{
char input[30];
if(access( "anagrams.txt", F_OK ) != -1) {
FILE *ptr_file;
char buf[1000];
ptr_file =fopen("anagrams.txt","r"); if (!ptr_file)
return 1;
while (fgets(buf,1000, ptr_file)!=NULL)
printf("%s",buf);
fclose(ptr_file);
printf("\n");
}
else{ //if file does not exist
printf("\nFile not found!\n");
}
return 0;
}
Code to find if the text are anagrams:
#include <stdio.h>
int find_anagram(char [], char []);
int main()
{
char array1[100], array2[100];
int flag;
printf("Enter the string\n");
gets(array1);
printf("Enter another string\n");
gets(array2);
flag = find_anagram(array1, array2);
if (flag == 1)
printf(" %s and %s are anagrams.\n", array1, array2);
else
printf("%s and %s are not anagrams.\n", array1, array2);
return 0;
}
int find_anagram(char array1[], char array2[])
{
int num1[26] = {0}, num2[26] = {0}, i = 0;
while (array1[i] != '\0')
{
num1[array1[i] - 'a']++;
i++;
}
i = 0;
while (array2[i] != '\0')
{
num2[array2[i] -'a']++;
i++;
}
for (i = 0; i < 26; i++)
{
if (num1[i] != num2[i])
return 0;
}
return 1;
}
You can try something like this:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MAXLINE 1000
#define MAXLETTER 256
int is_anagram(char *word1, char *word2);
void check_lines(FILE *filename);
int cmpfunc(const void *a, const void *b);
void convert_to_lowercase(char *word);
int
main(int argc, char const *argv[]) {
FILE *filename;
if ((filename = fopen("anagram.txt", "r")) == NULL) {
fprintf(stderr, "Error opening file\n");
exit(EXIT_FAILURE);
}
check_lines(filename);
fclose(filename);
return 0;
}
void
check_lines(FILE *filename) {
char line[MAXLINE];
char *word1, *word2, *copy1, *copy2;
while (fgets(line, MAXLINE, filename) != NULL) {
word1 = strtok(line, "#");
word2 = strtok(NULL, "\n");
copy1 = strdup(word1);
copy2 = strdup(word2);
convert_to_lowercase(copy1);
convert_to_lowercase(copy2);
if (is_anagram(copy1, copy2)) {
printf("%s#%s - Anagrams!\n", word1, word2);
} else {
printf("%s#%s - Not Anagrams!\n", word1, word2);
}
}
}
void
convert_to_lowercase(char *word) {
int i;
for (i = 0; word[i] != '\0'; i++) {
word[i] = tolower(word[i]);
}
}
int
is_anagram(char *word1, char *word2) {
qsort(word1, strlen(word1), sizeof(*word1), cmpfunc);
qsort(word2, strlen(word2), sizeof(*word2), cmpfunc);
if (strcmp(word1, word2) == 0) {
return 1;
}
return 0;
}
int
cmpfunc(const void *a, const void *b) {
if ((*(char*)a) < (*(char*)b)) {
return -1;
}
if ((*(char*)a) > (*(char*)b)) {
return +1;
}
return 0;
}
Since this looks like a University question, I won't provide a full solution, only a hint.
All you have to do is replace the stdin input part of the anagram-finding file with the code you wrote to read from a file: it's as simple as changing
printf("Enter the string\n");
gets(array1);
printf("Enter another string\n");
gets(array2);
to
// before program:
#define SIZE 1000
// inside main
if (access("anagrams.txt", F_OK) == -1){
printf("\nFile not found!\n");
return 1; // Abort the program early if we can't find the file
}
FILE *ptr_file;
char buf[1000];
ptr_file = fopen("anagrams.txt","r");
if (!ptr_file)
return 1;
char array1[SIZE], array2[SIZE];
while (fgets(buf, 1000, ptr_file)!=NULL){
// do all your anagram stuff here!
// there is currently one line of the input file stored in buf
// Hint: You need to split buf into array_1 and array_2 using '#' to separate it.
}
fclose(ptr_file);
printf("\n");
Additional comments:
Don't ever ever ever use gets. gets doesn't check that the string it writes to can hold the data, which will cause your program to crash if it gets input bigger than the array size. Use fgets(buf, BUF_SIZE, stdin) instead.
Beautiful code is good code. People are more likely to help if they can read your code easily. (fix your brackets)
Just for interest, a more efficient algorithm for checking anagrams is to use qsort to sort both arrays, then a simple string matcher to compare them. This will have cost O(mnlog(m+n)), as opposed to O(m^2 n^2), awith the current algorithm
You need to split every line you read by fgets (as you did) in to two strings, and pass them to your find_anagram function. You can do that using strtok:
int main()
{
int flag;
char buf[1000];
FILE *ptr_file;
//Check file existence
//Open the file for reading
while (fgets (buf, 1000, ptr_file) != NULL)
{
char *array1 = strtok(buf, "#");
char *array2 = strtok(NULL, "\n");
flag = find_anagram (array1, array2);
//Check flag value to print your message
}
return 0;
}
//put your find_anagram function
Don't forget to #include <string.h> to use strtok().
I am trying to write a code that simulates an Anti-Virus scan, it scans 5 specific files and then creates a file named AntiVirusLog.txt. In this file it writes the results, for example PSY.avi INFECTED. An infected file is a file that contains the string in the file youtubesign.
My problem is when I try to print in the results to the file AntiVirusLog.txt it does not print anything and leaves the file blank.
My code:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<dirent.h>
#define BUZZ_SIZE 1024
int fast_scan(char *fname, char *str, FILE *fs);
int slow_scan(char *fname, char *str, FILE *fs);
int main(int argc, char *argv[])
{
char name[100];
char choice[5];
char buff[BUZZ_SIZE];
FILE *f7, *f2;
struct dirent *de;
DIR *dr = opendir(argv[1]);
if (dr == NULL) // opendir returns NULL if couldn't open directory
{
printf("Could not open current directory");
return 0;
}
f2 = fopen(argv[2], "rb");
f7 = fopen("AntiVirusLog.txt", "wt");
printf("Welcome to Amnon's Anti-Virus program\n which scan would you like to choose?:\n");
printf("Fast: check only the first and the last 20% of the file\n Slow: Checks the entire file\n");
printf("Enter fast for a fast scan and slow for a slow scan\n");
scanf("%s", choice);
if ((strcmp(choice, "slow"))==0)
{
while ((de = readdir(dr)) != NULL)
{
strcpy(name, argv[1]);
strcat(name, de->d_name);
if((fgets(buff, BUZZ_SIZE, f2)) != NULL)
{
slow_scan(name, buff, f7);
}
}
}
if ((strcmp(choice, "fast")) == 0)
{
while ((de = readdir(dr)) != NULL)
{
strcpy(name, argv[1]);
strcat(name, de->d_name);
if ((fgets(buff, BUZZ_SIZE, f2)) != NULL)
{
fast_scan(name, buff, f7);
}
}
}
printf("The scan was made successfuly, check the file AntiVirusLog.txt to see the results\n");
closedir(dr);
fclose(f2);
fclose(f7);
system("PAUSE");
return (0);
}
int slow_scan(char *fname, char *str, FILE *fs)
{
int findres = 0;
FILE *fp;
char temp[BUZZ_SIZE];
if ((fopen_s(&fp, fname, "rb")) != NULL)
{
return(-1);
}
while ((fgets(temp, BUZZ_SIZE, fp)) != NULL)
{
if ((strstr(temp, str)) != NULL)
{
fprintf(fs, "%s INFECTED\n", fname);
findres++;
}
}
if (findres==0)
{
fprintf(fs, "%s NOT INFECTED\n", fname);
}
fclose(fp);
return(0);
}
int fast_scan(char *fname, char *str, FILE *fs)
{
int findres=0;
int i, j, len, partlen;
FILE *fp;
if ((fopen_s(&fp, fname, "rb")) != NULL)
{
return(-1);
}
fseek(fp, 0, SEEK_END);
len = ftell(fp);
partlen = (len * 20) / 100;
char *temp=malloc(partlen);
while ((fgets(temp, BUZZ_SIZE, fp)) != NULL)
{
for (i = 0; i < partlen; i++)
{
if (temp[i]=str[i])
{
findres++;
}
if (temp[i] != str[i])
{
i = partlen + 1;
}
if (findres == partlen)
{
fprintf(fs, "%s INFECTED\n", fname);
i = partlen + 1;
}
}
for (j = len - partlen; j < len; j++)
{
if (temp[j] = str[j])
{
findres++;
}
if (temp[j] != str[j])
{
j = partlen + 1;
}
if (findres == partlen)
{
fprintf(fs, "%s INFECTED\n", fname);
j = partlen + 1;
}
}
}
if (findres!= partlen)
{
fprintf(fs, "%s NOT INFECTED\n", fname);
}
fclose(fp);
return(0);
}
There are primarily two major issues with your code
Point 1: In your code, for the series of calls like
search_sign(argv[1], buff, f7);
you're using buff uninitialized. The buff is then passed as the second parameter of search_sign(), (to be accepted as str) which is again used as the search string in strstr().
As buff is an automatic local variable, the initial content (value) is garbage (indeterminate) and hence , when used as the search key in strstr(), will invoke undefined behaviour.
Point 2: That said, as my previous comment, you should always be checking the success of fopen() call(s) before using the returned file pointer any further.
I have used some of the advices listen and found some fixes of my own and now it works perfectly! the updated code looks like this:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define BUZZ_SIZE 1024
int search_sign(char *fname, char *str, FILE *fs);
int main(int argc, char *argv[])
{
char buff[BUZZ_SIZE];
FILE *f,*f7;
f7 = fopen("AntiVirusLog.txt", "wt");
f = fopen(argv[1], "rb");
if ((fgets(buff, BUZZ_SIZE, f)) != NULL)
{
search_sign(argv[2], buff, f7);
search_sign(argv[3], buff, f7);
search_sign(argv[4], buff, f7);
search_sign(argv[5], buff, f7);
search_sign(argv[6], buff, f7);
}
printf("The scan was made successfuly, check the file AntiVirusLog.txt to see the results\n");
fclose(f);
fclose(f7);
system("PAUSE");
return (0);
}
int search_sign(char *fname, char *str, FILE *fs)
{
int findres = 0;
FILE *fp;
char temp[BUZZ_SIZE];
if ((fopen_s(&fp, fname, "rb")) != NULL)
{
return(-1);
}
while ((fgets(temp, BUZZ_SIZE, fp)) != NULL)
{
if ((strstr(temp, str)) != NULL)
{
fprintf(fs, "%s INFECTED\n", fname);
findres++;
}
}
if (findres==0)
{
fprintf(fs, "%s NOT INFECTED\n", fname);
}
fclose(fp);
return(0);
}
I want to write a program which print all numbers found in a file and then add them up. I have two problems:
How to add up the numbers I've printed?
Why in output_file do I have so many commas:
Here's my code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define CHUNK 12
char *getWord(FILE *infile);
void clean(char *dirty);
char *getWord(FILE *infile)
{
char *word, *word2;
int length, cursor, c;
word = (char*)malloc(sizeof(char)*CHUNK);
if(word == NULL) return NULL;
length = CHUNK;
cursor = 0;
while(!isspace(c = getc(infile)) && !feof(infile))
{
word[cursor] = c;
cursor++;
if(cursor >= length)
{
length += CHUNK;
word2 = (char*)realloc(word, cursor);
if(word2 == NULL)
{
free(word2);
return NULL;
}
else
{
word = word2;
}
}
}
word[cursor] = '\0';
return word;
}
void clean(char *dirty)
{
int i = 0, j = 0;
char *temp;
temp = strdup(dirty);
while(i < strlen(temp))
{
if(isdigit(temp[i]))
{
dirty[j] = temp[i];
j++;
}
i++;
}
dirty[j] = '\0';
free(temp);
}
int main(int argc, char *argv[])
{
char *word;
FILE *infile, *outfile;
if(argc != 3)
{
printf("Missing argument!\n");
exit(1);
}
infile = fopen(argv[1], "r");
if(infile != NULL)
{
outfile = fopen(argv[2], "w");
if(outfile == NULL)
{
printf("Error, cannot open the outfile!\n");
abort();
}
else
{
while(!feof(infile))
{
word = getWord(infile);
if(word == NULL)
{
free(word);
abort();
}
clean(word);
fputs(word, outfile);
fputs(",", outfile);
free(word);
}
}
}
else
{
printf("Error, cannot open the outfile!\n");
abort();
}
fclose(infile);
fclose(outfile);
return 0;
}
infile:
You are getting , because of this -
fputs(",", outfile);
It is related in structure to the echo unix command. The core of the program could be simplified to something along the following lines:
int c, need_comma = 0;
while ((c = fgetc(infile)) != EOF) {
if (isdigit(c)) {
fputc(c, outfile);
need_comma = 1;
}
else {
if (need_comma == 1) {
fputc(',', outfile);
need_comma = 0;
}
}
}
this removes the need for getWord and clean functions.
This is just the printing part. the intermediate file is in CSV format,
which is structured and easy to parse and add the numbers (and print the
result to another file).