how to compare string value in C (strcmp)

[need some help]

Hi,

Can you please help me...I am not able solve this issue. I have a array AttValName[Att][v] which has following values,
Att=Outlook,

AttValName[Att][1]=sunny
AttValName[Att][2]=Rain
AttValName[Att][3]=overcast

and data is like,

1.sunny,hot,mil d,play
2. sunny,normal,hi gh,Don'y play
3....
4...

and I need to get record number when AttValName[Att][v] = "sunny"
Is is possible to do that? If yes, Can you please tell me how?

Thanks.

[weaknessforcats]

Use the strcmp() function to compare C strings. Check your docset.

You may have other problems based on your code snippet. Keep us advised how you are progressing.

[need some help]

I understand I have to use strcmp() but, how do I retrive each record from the file ..
here at the place of ??? how do I get my string from the file and its record no???
in C.

strcmp(AttValNa me[Att][v]," ???")
1. sunny, high,low, play


thanks,

Use the strcmp() function to compare C strings. Check your docset.

You may have other problems based on your code snippet. Keep us advised how you are progressing.

[weaknessforcats]

You will have to read the disc file into arrays. You show data like:

sunny, high,low, play


You can read this data into a buffer you allocate. The buffer would contain the data from one record. Maybe:

[CODE=cpp]
char* myRecords[10]; //enough for 10 disc records

//Allocate memory for a buffer that can hold data for one record:
char* buffer = malloc(a large enough number for 1 disc record);
//Read the disc into the buffer.
--how to do this omitted ---
//Then put the array in the myRecords array
myRecords[i] = buffer;
[/CODE]

Your record numbers are now the subscripts of the myRecords array. All of the values:

sunny, high,low, play

are in one string. You will then process the string to see the values. Here's where the strcmp() will come in.

[need some help]

Hi

Thanks for the help. When I will get whole string in myrecord[] then to get only "sunny" from that string do I have to use strtok() ? because I just want to compare AttvalName[Att][v] with only sunny not the whole line.

You will have to read the disc file into arrays. You show data like:

sunny, high,low, play


You can read this data into a buffer you allocate. The buffer would contain the data from one record. Maybe:

[CODE=cpp]
char* myRecords[10]; //enough for 10 disc records

//Allocate memory for a buffer that can hold data for one record:
char* buffer = malloc(a large enough number for 1 disc record);
//Read the disc into the buffer.
--how to do this omitted ---
//Then put the array in the myRecords array
myRecords[i] = buffer;
[/CODE]

Your record numbers are now the subscripts of the myRecords array. All of the values:

sunny, high,low, play

are in one string. You will then process the string to see the values. Here's where the strcmp() will come in.

[AdrianH]

Hi

Thanks for the help. When I will get whole string in myrecord[] then to get only "sunny" from that string do I have to use strtok() ? because I just want to compare AttvalName[Att][v] with only sunny not the whole line.

That is certainly one way of doing it. Try looking up the str functions and you will find some functions to search a string for a substring.


Adrian

[need some help]

To get the data as you said I am writing following code but its not working. Can you please tell me where I am wronge?


[code=c]#include <stdio.h>
#include <string.h>

main()
{
char Fn[100];
FILE *Nf;
char *buffer[100];
char *myrecord[10];
int i=0,x=0;

// strcpy(Fn,wthr) ;
// strcat(Fn,".dat a");
// printf("file name is : %s \n",FileName) ;

Nf=fopen("wthr. data","r");

fread(buffer,0, 100,Nf);
myrecord[i] = buffer[i];
i++;

while(!feof(Nf) )
{
fscanf(Nf,"%f ", &(myrecord[x]));
x++;

}
fclose(Nf);
}[/code]

Thanks.

That is certainly one way of doing it. Try looking up the str functions and you will find some functions to search a string for a substring.


Adrian

[AdrianH]

To get the data as you said I am writing following code but its not working. Can you please tell me where I am wronge?


[code=c]#include <stdio.h>
#include <string.h>

main()
{
char Fn[100];
FILE *Nf;
char *buffer[100];
char *myrecord[10];
int i=0,x=0;

// strcpy(Fn,wthr) ;
// strcat(Fn,".dat a");
// printf("file name is : %s \n",FileName) ;

Nf=fopen("wthr. data","r");

fread(buffer,0, 100,Nf);
myrecord[i] = buffer[i];
i++;

while(!feof(Nf) )
{
fscanf(Nf,"%f ", &(myrecord[x]));
x++;

}
fclose(Nf);
}[/code]

Thanks.

You have read in a big chunk of code using fread(), then you try and read in more data using fscanf(). Why? What is your intent?


Adrian

[Savage]

You have read in a big chunk of code using fread(), then you try and read in more data using fscanf(). Why? What is your intent?


Adrian

Yes,and what is BTW purpose of setting size of each data item to 0?

fread(buffer,0//Size of item which is been readed n times,100//n,Nf);

Savage

[AdrianH]

Yes,and what is BTW purpose of setting size of each data item to 0?

fread(buffer,0//Size of item which is been readed n times,100//n,Nf);

Savage

Doh! Missed that one. ;) You aren't reading in anything since 0*anything is 0.


Adrian

[Savage]

Doh! Missed that one. ;) You aren't reading in anything since 0*anything is 0.


Adrian

Don't worry,it can happen to anyone.

:)

Savage

[AdrianH]

Don't worry,it can happen to anyone.

:)

Savage

Not me. :cry: I'm loosing my touch. :bawl: LOL JK


Adrian

[Savage]

Not me. :cry: I'm loosing my touch. :bawl: LOL JK


Adrian

LOL!

Savage

[need some help]

[code=c]#include<stdio. h>
main()
{

char buffer[100];
// char myrec[100];
FILE *Nf;
char *c;
char *myrec[10];
int i = 0, j;

Nf = fopen("wthr.dat a", "r");

do {
c = fgets(buffer, 100, Nf);
myrec[i] = buffer;
printf("myrecor d is : %s \n", myrec[i]);
i = i + 1;

if (c != NULL)
printf("%s", buffer);
} while (c != NULL);

for (j = 0; j < 10; j++) {
printf("records are : %s \n", myrec[j]);
}

fclose(Nf);

}[/code]

now its printing with first 2 printfs but why its not printing at printf in for loop?

LOL!

Savage

[Savage]

]#include<stdio. h>
main()
{

char buffer[100];
// char myrec[100];
FILE *Nf;
char *c;
char* myrec[10];
int i=0,j;

Nf = fopen("wthr.dat a", "r");

do
{
c= fgets(buffer,10 0,Nf);
myrec[i] = buffer;
printf("myrecor d is : %s \n",myrec[i]);
i=i+1;

if (c != NULL)
printf("%s", buffer);
} while (c != NULL);

for(j=0;j<10;j+ +)
{
printf("records are : %s \n",myrec[j]);
}

fclose(Nf);

}[/CODE]
now its printing with first 2 printfs but why its not printing at printf in for loop?

How do u mean not printing?

BTW,ur do-while loop is not completly good designed.It should increase i only if c!=NULL,and it should break before inputing data from buffer to myrec if c==NULL,so it should look like:

[CODE=c]do{
if((c=fgets(buf fer,100,Nf))=NU LL) break;
myrec[i]=buffer;
//print record
if(c!=NULL) //print buffer;

}while(1);[/CODE]

Savage