Thread: Linear search function accessing string in a struct

I currently have a file which allows inputs to record different transistor types. I then have the task of accessing this structure, find a certain manufacturer ID, and print the information about this particular transistor.

My problem is accessing the array to search through.
Here is my code:

Code:

#include "stdio.h"
const int IDLEN=30; //All constant values defined
const int POLARITYLEN=3;
const int MAXSTOCKITEMS=10;
    
//First structure defined
struct TransistorRec {
	char manufacturersID[IDLEN];
	char polarity[POLARITYLEN];
	float power;
	float gain;
	int stock;
};


//Function prototype
int linearSearch ( struct TransistorRec ID[], const char *searchKey, int arraySize);


int main()
{
	int total,i;
	char ManIDS;
	char manarray[IDLEN];
	TransistorRec a[10];
	//Ask user how many transistors are in stock
	printf("How many different transistors are in stock?  ");
	scanf("%i",&total);
	
	//If statment to make sure that not too many items are in stock
	if(total>MAXSTOCKITEMS)
	{
     printf("To many items in stock, choose a smaller value: ");
     scanf("%i",&total);
     }
     
	//Ask user to enter in all neccesary data
	for ( i = 0; i <total; i++){
		printf("Enter manufacturer's ID, polarity, power, gain, stock :\n");
	scanf("%s %s %f %f %i",a[i].manufacturersID,a[i].polarity,&a[i].power,&a[i].gain,&a[i].stock);
	}
	
	//Now to print this information in a tabular format
	//Print all required headers
	printf("\n\nManID\tPolarity\tMax Power\tCurrent Gain\tNo. in stock");
	
	//Now to print out all data using a loop
	for ( i = 0; i <total; i++)
	{
        printf("\n%s \t%s \t\t%4.1f \t\t%4.1f \t\t%i",a[i].manufacturersID,a[i].polarity,a[i].power,a[i].gain,a[i].stock);
        }
    //Search for manufacxturer ID


     printf("Enter manufacturer ID to search for: ");
     scanf("%s",&ManIDS);
     int index = linearSearch ( struct TransistorRec ID[], ManIDS, total);


    if (index < 0) { // search string was not found
        printf("Search string not found!\n");
    }
    else {
        printf("String %s found at index %d\n", manufacturersID[index], index);
    }


 


	return 0;
	
}

My search function is as follows:

Code:

#include "stdio.h"


int linearSearch (struct TransistorRec ID[], const char *searchKey, int arraySize) {
    for (int i = 0; i < arraySize; ++i) {
        if (searchKey == ID[i].manufacturersID)
            return i;
    }


    // We didn't find the searchKey in the Array
    return -1;
}

The errors I am currently getting are on line 54 'expected primary-expression before "struct"' and on line 60 ' 'maunfacturersID' undeclared'

I am very new to the c language so sorry if my code i sloopy and/or confusing.

Any help on how I can search for the requested manufacturers ID would be greatly appreciated. Thanks!

Your line numbers don't match but I think you have problems with these lines:

Code:

const int IDLEN=30; //All constant values defined
const int POLARITYLEN=3;
const int MAXSTOCKITEMS=10;
//First structure defined
struct TransistorRec {
    char manufacturersID[IDLEN];
    char polarity[POLARITYLEN];

Don't you get an error here?

Code:

TransistorRec a[10];    // missing "struct" 
...
int index = linearSearch ( struct TransistorRec ID[], ManIDS, total);  
// You have to call linearSearch() with the actual array (a)
...
printf("String %s found at index %d\n", manufacturersID[index], index);
// "manufacturersID" is a member of a struct, thus you can't use it without a leading struct object
// You used it correctly a few lines above and inside linearSearch()

Bye, Andreas

Code:

if (searchKey == ID[i].manufacturersID)

You cannot compare c-strings this way.
Use strcmp().
Kurt

What happens if the user enters a number larger than the max more than twice?

Also you're not using your constant MAXSTOCKITEMS in your array declaration, which you should.

Code:

struct TransistorRec a[ MAXSTOCKITEMS ];

Thanks for all the help so far! I am still a bit unsure of how to call my function. I have changed Linear search to the following:

Code:

#include "stdio.h"


int linearSearch (struct TransistorRec ID[], const char *searchKey, int arraySize) {
    for (int i = 0; i < arraySize; ++i) {
        if (strcmp(ID[i],searchKey)==0)
            return i;
    }


    // We didn't find the searchKey in the Array
    return -1;
}

and then call the function with this

Code:

int index = linearSearch (a[].manufacturersID, ManIDS, total);

This is where I am getting an error saying "expected primary-expression before ']' token"

Thanks in advance!

You want to pass an array of struct TransistorRec to that function.
that would be

Code:

int index = linearSearch ( a , ManIDS, total);

Kurt

Thanks, but now doing that I get errors saying "invalid conversion from 'char' to 'const char*' As well as 'initializing argument 2 of 'int linearSearch(TransistorRec*, const char*, int)' '
any suggestions?

ManIDS is currently defined to be a single character.
It is supposed to be an array of characters
try

Code:

char ManIDS[IDLEN];

Kurt

As well as 'initializing argument 2 of 'int linearSearch(TransistorRec*, const char*, int)' '

To me, this means that you are passing the second argument of the function without initializing it.

Originally Posted by ZuK

ManIDS is currently defined to be a single character.
It is supposed to be an array of characters
try

Code:

char ManIDS[IDLEN];

Kurt

Changing ManIDS to an array as suggested, returns a list of errors in my function.
All errors come from the following line:
-int linearSearch (ID, const char *searchKey, int arraySize)

The list of errors are as follows:
- ID was not declared in this scope
- expected primary expression before "const"
-expected primary expression before "int"
- initializer list treated as compound expression
- expected ',' or ';' before '{' token

Also at the moment I am not telling my function to look into a.manufacturersID, just a, could that be a source of error.

Thanks again for the help provided!

Originally Posted by thekid

Changing ManIDS to an array as suggested, returns a list of errors in my function.
All errors come from the following line:
-int linearSearch (ID, const char *searchKey, int arraySize)

Now you have to explain to us, how changing ManIDS also changed the function prototype.

Bye, Andreas