I'm new to programming in c and I've come across a problem with my file system. The aim of this program is for a user to enter a message and that message gets stored in a text file. After the users message gets stored in a text file, they have the choice to 'read' a messaged their loved one has sent to them.
char SingleLine[150];
FILE * filePointer;
FILE * fpointer;
char mess[10];
char reply[100];
case 4:
printf("enter a message: ");
fscanf(stdin, "%s", mess);
filePointer = fopen("gift.txt", "w");
fprintf(filePointer, "%s \n", mess);
printf("you said %s \n", mess);
printf("they wrote something back?, would you like to read it? yes or no? \n ");
scanf("%s", &reply);
if ((toupper(reply[0]) == 'Y') && (toupper(reply[1]) == 'E') && (toupper(reply[2]) == 'S'))
{
printf("you said %s is that true???", &reply);
printf("ok loading...\n");
fpointer = fopen("luvtracey.txt", "r");
while (!feof(fpointer))
fgets(SingleLine, 150, fpointer);
puts(SingleLine);
}
else if ((toupper(reply[0]) == 'N') && (toupper(reply[1]) == 'O'))
{
printf("wow ignorant \n");
}
else
{
printf("your not having it anymore");
}
}
But when this code runs firstly, when a user enters a message with no spaces, it'll get stored. But when you add spaces, the message would get chopped in half and the first bit would get stored. Secondly, when you type 'yes' (when you want to see what your loved one has sent) it crashes completely but i don't understand why. Also its not retrieving the information in the 'luvtracey.txt' file which has words in it.
I accept feedback and i just want to say thank you to those in advance who help me solve these problems.
~Neamus
if ((toupper(reply[0]) == 'Y') && (toupper(reply[1]) == 'E') ...
You can convert the string to lowercase or uppercase and strcmp, rather than checking letters one by one.
while (!feof(fpointer))
fgets(SingleLine, 150, fpointer);
puts(SingleLine);
Don't use feof. Instead check if fgets succeeds. Presumably you want to print each line in the file, so don't print the line after the loop finishes. You also need error checks to make sure the file was opened successfully. Example:
#include <stdio.h>
#include <ctype.h>
#include <string.h>
int main(void)
{
char buffer[150];
printf("enter a message: ");
fscanf(stdin, "%s", buffer);
printf("you said %s \n", buffer);
FILE *fp = fopen("gift.txt", "w");
fprintf(fp, "%s \n", buffer);
fclose(fp);
printf("yes or no? ");
scanf("%s", buffer);
for(int i = 0, len = strlen(buffer); i < len; i++)
buffer[i] = (char)tolower(buffer[i]);
if (strcmp(buffer, "yes") == 0)
{
fp = fopen("luvtracey.txt", "r");
if(!fp)
{
printf("can't open...\n");
}
else
{
while(fgets(buffer, sizeof(buffer), fp))
printf("%s", buffer);
fclose(fp);
}
}
return 0;
}
Related
I a trying to take file name as argument and write strings using loop until user enter "-1".
problem 1: writing is not happening in text file and always shows empty
problem 2: cannot compare input -1 and "-1" . Always runs the else statements.
Note: I also tried fputs but it did not work that time either.
FILE *fp = fopen(argv[1], "a");
//fseek(fp, 0, SEEK_END);
char str[100];
printf("enter string\n");
bool flag = true;
while (flag == true) {
//printf("\nEnter data to append: ");
fflush(stdin);
fgets(str, 100, stdin);
if (strcmp(str, "-1") == 0) {
break;
} else {
fprintf(fp, "%s", str);
printf("Text written in file: %s\n", str);
}
}
fclose(fp);
Writing don't happen because of strcmp, I'm showing you my version of this with atoi.
#include <stdio.h>
#include <stdlib.h>
#define buffer 128
int main(int argc, char *argv[])
{
char str[buffer];
int flag = 1;
FILE *fp = fopen(argv[1], "w+"); //I prefer using write mode and not append
if(fp==NULL)
{
printf("Error opening file.\n"); //here you control if the file is opening correctly
exit(EXIT_FAILURE);
}
while(flag) //you don't need to write while(flag==true) (that's not wrong)
{
printf("Insert string: ");
scanf("%s", str);
if(atoi(str)==1) //the function strcmp as you wrote it will break after the
break; //first cicle, use atoi, it returns 1 if the string is a number
fprintf(fp, "%s\n", str); //the \n is to get the next string on the next row
}
fclose(fp);
return 0;
}
If you want to make it work with strcmp your if statement should be if(strcmp(str, "-1\n")) because fgets reads also the \n character.
Because fget() reads new line character.
So once you do comparation, It looks like:
strcmp("-1\n", "-1");
or
strcmp("-1\n\r", "-1");
You will never break the loop.
To remove newline character, let try:
strtok(str, "\n");
or
strtok(str, "\r\n");
I created a file and filled it with some entries. However, I want to read this file and show it on the screen. Also, after showing the entries, I want it to be deleted with my permission. But I am stuck at this point please help me.
EDIT: Code is updated but still couldn't figure it out how to do :/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
char name[20], surname[20], city[30], country[30], gender[15];
int count = 0;
int main() {
FILE *f1;
f1 = fopen("C:\\FurkanArslan.txt", "r+");
while (count < 10) { // every step provides 5 new data, so 5*10 will provide 50 data in total.
printf("\n*Please enter required information: \n");
printf("Name :"); scanf("%s", name);
printf("Surname:"); scanf("%s", surname);
printf("Country:"); scanf("%s", country);
printf("City :"); scanf("%s", city);
printf("Gender :"); scanf("%s", gender);
fprintf(f1, " %s | %s | %s | %s | %s\n\n", name, surname, gender, city, country);
count++;
}
fclose(f1);
printf("\n<<<<<%d data has been successfully saved!>>>> \n", count * 5);
printf("-------------------------------------\n");
f1 = fopen("C:\\FurkanArslan.txt", "r");
char c, answer;
while ((c = fgetc(f1)) != EOF)
putchar(c); // In this part I displayed file on the screen.
printf("\n\n <<<< %d entries are displayed on the screen! >>>>", count * 5);
printf("\n\nWould you like to remove your file [Y/N] ?");
scanf(" %c", &answer);
if (answer == 'y' || answer == 'Y') {
remove("f1");
printf("\n\n***File successfully removed!");
}
return 0;
}
In order to show the content of a file you have to open it and read it letter by letter, after that, you can use the putchar function to output the current character
FILE *fp = fopen("path/to/file.txt","r");
char c;
while((c=fgetc(fp))!=EOF)
putchar(c);
fclose(fp);
after that to remove a file you need to use the remove function, which receives the name of the file as paramter.
remove("my_file.txt");
There are multiple issues in your code:
there is no need to make the variables and arrays global, just define them in the body of the main() function.
you should tell scanf() the maximum number of characters to store in the destination array with a length specifier in the format string (eg: "%19s") and check for conversion success.
the variable c used in the reading loop must have type int for proper detection of EOF. fgetc() returns a positive byte value if successful and the special negative value EOF at end of file.
you do not need to reopen the file after writing to it. Sine you opened it for update mode, you can just seek back to the beginning of the file with rewind(f1) or fseek(f1, 0L, SEEK_SET).
the file is open for read and update mode ("r+"): it will fail if the file does not exist. You should open it in write and update mode with "w+" to create or truncate it.
you should check that fopen succeeds at opening the file, otherwise you invoke undefined behavior passing a null stream pointer to fprintf.
to remove the file, remove() takes the filename as its argument. You must close the file before attempting to remove it.
Here is a modified version:
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main() {
const char *filename = "C:\\FurkanArslan.txt";
char name[20], surname[20], city[30], country[30], gender[15];
int count = 0;
FILE *f1 = fopen(filename, "w+");
if (f1 == NULL) {
printf("Cannot open file %s.\n", filename);
return 1;
}
while (count < 10) { // every step provides 5 new data, so 5*10 will provide 50 data in total.
printf("\n*Please enter required information: \n");
printf("Name :"); if (scanf("%19s", name) != 1) break;
printf("Surname:"); if (scanf("%19s", surname) != 1) break;
printf("Country:"); if (scanf("%29s", country) != 1) break;
printf("City :"); if (scanf("%29s", city) != 1) break;
printf("Gender :"); if (scanf("%14s", gender) != 1) break;
fprintf(f1, " %s | %s | %s | %s | %s\n\n", name, surname, gender, city, country);
count++;
}
printf("\n<<<<< %d data has been successfully saved to %s! >>>>\n",
count * 5, filename);
printf("-------------------------------------\n");
rewind(f1);
int c;
while ((c = fgetc(f1)) != EOF)
putchar(c);
printf("\n\n <<<< %d entries are displayed on the screen! >>>>\n", count);
fclose(f1);
printf("\nWould you like to remove your file [Y/N] ?");
char answer;
if (scanf(" %c", &answer) == 1 && (answer == 'y' || answer == 'Y')) {
if (remove(filename)) {
printf("\n\n***Error removing file %s: %s\n",
filename, strerror(errno));
} else {
printf("\n\n***File %s successfully removed!\n", filename);
}
}
return 0;
}
I need to write a C program to fetch data from one file and write it to another file, without using user defined functions. My requirements are to:
Search customer details by Name.
Store the transaction data (paid amount) in another text file.
I did the code to search by name. But its not working,
#include <stdio.h>
#include <stdlib.h>
int main () {
char name[10], nic[10], mobile[10];
char fname[10], fnic[10], fmobile[10];
char choice;
int amount;
FILE *cfptr;
printf("Enter search type - \n 1. NAME \n 2. NIC \n 3.MOBILE \n ----> ");
scanf("%c", &choice);
printf("Enter search text : ");
scanf("%s", &name);
cfptr = fopen ("customer.dat", "r");
while (!feof(cfptr)){
fscanf(cfptr, "%s %s %s", fname, fnic, fmobile);
printf("Read Name |%s|\n", fname );
printf("Read NIC |%s|\n", fnic );
printf("Read Mobile |%s|\n", fmobile );
}
fclose(cfptr);
scanf("%d", &amount);
return(0);
}
customer.dat File
Shan 100012 200202
Marsh 121213 667675
Kim 126573 663412
This code is not complete asI cant filter the single name assigning
if(name == fname)
as am getting
assignment to expression with array type error
Can any one complete me the code to search and save to another file so I can do the amount calculation part?
int Search_in_File(char *fname, char *str) {
FILE *fp;
int line_num = 1;
int find_result = 0;
char temp[512];
//gcc users
//if((fp = fopen(fname, "r")) == NULL) {
// return(-1);
//}
//Visual Studio users
if((fopen_s(&fp, fname, "r")) != NULL) {
return(-1);
}
while(fgets(temp, 512, fp) != NULL) {
if((strstr(temp, str)) != NULL) {
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);
}
few comments:
when scanning the choice, read it as an integer and not as a character.
scanf("%c", &choice); // change to scanf("%d", &choice);
single '=' is an assigment, you meant comparison which is double '=='
if(name = fname) // comparison is if(name == fname)
in order to compare string, do not use '==' operator. use strcmp or implement an equivalent of strcmp.
Thanks for the effort, As with changes, I have changed my code as below and its working. Without checking with the name, I alternately checked with the nic.
#include <stdio.h>
int main(void){
int nic, n, mobile;
char name[30];
FILE *aPtr;
aPtr = fopen("Details.txt","w");
if(aPtr == NULL){
printf("File cannot be opened");
return -1;
}
printf("Enter nic to search - ");
scanf("%d", &n);
fscanf(aPtr, "%d %-s %d", &nic, name, &mobile);
while(!feof(aPtr)){
if(nic == n){
Printf("%d %s %d \n", nic, name, mobile);
}
fscanf(aPtr, "%d %s %d", &nic, name, &mobile);
}
fclose(aPtr);
return 0;
}
I'm writing a simple exercise app in C, which should ask user if he want write something to file or read the file. I want give name to the file and then input some text in console. I want use that text to save it to the file.
The problem is that, when I already give name to the file, I can't input data to the console and by this I can't save these datas to the text file. In addition, the while loop ignores my 'y' to restart the program again. Furthermore, when I want use reading file then it really does, program works, but it also adds instruction from default (printing just error) but I don't want that, just only read from file and print it to the console.
Can someone explain me what I'm doing wrong and how to solve this? I'd be grateful.
Here's my code:
int main()
{
FILE *file;
char nameFile[32];
char string[500];
char ans[2];
int choice;
do{
printf("What do you want to do?\n");
printf("1. Write text to file\n");
printf("2. Read text file\n");
scanf("%d", &choice);
switch (choice) {
case 1:
printf("Give name to the file (*.txt).\n");
scanf("%s", nameFile); //This line skips me to line where program ask user if restart the program (I have no idea why :()
system("clear");
file=fopen(nameFile, "w");
if(file!=NULL){
printf("Input text:\n");
scanf("%[^\n]", string); //<--- HERE I'cant input text to console, seems like scanf doesn't work.
fprintf(file, "%s", string);
printf("\n\t\t\t-----------Ended writing.------------\n");
fclose(file);
}
else
{
printf("Could not open the file.");
return -1;
}
break;
case 2:
printf("Give name to the file (*.txt)");
scanf("%s", nameFile);
system("clear");
file=fopen(nameFile, "r");
if(file!=NULL){
while (!feof(file)) {
fscanf(file, "%s", string);
printf("%s\n",string); //After printing data from text file, adds instruction from line , and that is printing Error. How to get rid of it?
}
}
else{
printf("Could not open the file.");
return -1;
}
default:
printf("Error.");
break;
}
printf("Do you want to restart the program? (y/*)"); //Even if I write 'y', program ends anyway :(
scanf("%s", ans);
}
while(ans=='y');
return 0;
}
https://ideone.com/aCYJR5
scanf("%[^\n]", string); doesn't work unless the input buffer is clear. Use instead scanf("%499s", string) where 499 is the size of the string minus 1.
Don't use while (!feof(file)){...}, use instead while(fscanf(file, "%500s", string) == 1){...}
Use while(ans[0]=='y') as suggested earlier. Or use
char ans;
scanf(" %c", &ans);//note the blank space before `%c`
while(ans == 'y')
You also forgot to break a switch statement. Try the following:
char c;
char ans;
do {
printf("What do you want to do?\n");
printf("1. Write text to file\n");
printf("2. Read text file\n");
scanf("%d", &choice);
switch(choice) {
case 1:
printf("Give name to the file (*.txt).\n");
scanf("%s", nameFile);
file = fopen(nameFile, "w");
if(file == NULL) { printf("Could not open the file."); return -1; }
printf("Input text:\n");
while((c = getchar()) != '\n' && c != EOF);
fgets(string, sizeof(string), stdin);
string[strcspn(string, "\r\n")]=0;
fprintf(file, "%s", string);
printf("\n\t\t\t-----------Ended writing.------------\n");
fclose(file);
break;
case 2:
printf("Give name to the file (*.txt)");
scanf("%s", nameFile);
file = fopen(nameFile, "r");
if(file == NULL) { printf("Could not open the file."); return -1; }
while(fgets(string, sizeof(string),file))
printf("%s\n", string);
fclose(file);
break;
}
printf("Do you want to restart the program? (y/*)");
scanf(" %c", &ans);
} while(ans == 'y');
See also
Why is “while ( !feof (file) )” always wrong?
How to clear input buffer in C?
your while should be
while(ans[0]=='n');
A char array is a string, you are trying to compare a whole string to the character 'y'. Also, it should "Loop while ans[0] is equal to 'n'" meaning keep going if the user specifies n.
I am writing a menu system in C, the code works correctly but for some reason the first first time the while loop is entered for the menu it skips the getchar() command and runs through the while loop again, but the second time round it works?
Any ideas as to why it does this?
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "structs.h"
int main(void)
{
FILE *fp = NULL;
char fileName[25], line[200], userInput = ' ';
int len;
while (fp == NULL)
{
printf("Enter The File To Load In: \n");
scanf("%s", fileName); // Ask User For File Name
fp = fopen(fileName, "r"); // Open File To Read
if (fp == NULL)
{
perror("Error While Loading File\n");
}
}
while (userInput != 'g')
{
printf(" |User System|\n");
printf("A) Save Current Data To A File\n");
printf("B) Enter Details\n");
printf("C) View Details\n");
printf("D) Amend Details\n");
printf("E) Search by Award Title\n");
printf("F) Search by Surname\n");
printf("G) Shut Down\n");
userInput = getchar();
if (userInput == 'c')
{
fgets(line, 200, fp);
len = strlen(line);
printf("%s", line);
userInput = getchar();
}
}
}
After 'scanf' use
getchar();
to consume extra newline. As 'scanf' can not discard newline, first iteration of 'getchar();' take the newline.
So you shold place getchar() after scanf as to consume extra newline('\n')
scanf("%s", fileName);
getchar();
It's better to use 'fgets' instead of scanf as file name may have space.
You can use 'fgets()' as
fgets(fileName, sizeof(fileName), stdin);
fileName[strlen(fileName)-1] = 0; //Replace newline with '\0' character