Thread: trouble writing stored data to output

You should check that fopen didn't fail (if it did, output == NULL). list_num looks like it should be the right thing. Do you have data in loadedSequences[list_num]? What are you getting?

here is more code to show what i am doing

Code:

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

typedef struct { char *name ; char data[1000000] ; int length ; int type ; char header[1000] ; } sequence ;

sequence loadedSequences[1000] ;

int nSequences = 0 ;
    
int main()
    {
        char std_input[1000] ;  // prev. buffer
        char header_data[1000] ;
        char seq_data[100000] ;
        char buffer[100000] ;
        char header_line[1000] ;
        
        FILE *input, *output ;
        
        char *seqName ;        
        char *command ;
        char *filename ;
        char *accession_id ;
    
        int list_num ;
        
        int i ;
        int c ;
        int n ;
        
        for(;;)
            {
                printf("SeqTool> ") ;
                
                fgets(std_input, 1000, stdin) ;
                fpurge(stdin) ;
                
                // Eliminating the newline character
                char *p = strchr(std_input, '\n') ;
                if (p) 
                    {
                        *p = '\0' ; 
                    } 
                                          
                command = strtok( std_input, " \t\n" ) ; 
                
////////////////// Load sequence in FASTA format //////////////////////////
                
                if( (strcmp ( command, "read" )) == 0 )
                    {
                        
                        filename = strtok(NULL, " \t\n" ) ; // collect filename                       
                        if( filename ) 
                            { 
                                input = fopen(filename, "r") ;
                                if ( !input )
                                    {
                                        perror(filename);
                                        continue ;
                                    }                                
                            }                            
                       
                        fgets( header_data, 1000, input) ; 
                                                
                        seqName = &header_data[1] ;   // After the > in FASTA format
                        
                        strcpy( header_line, seqName ) ;  
                        
                        accession_id = strtok(header_line, " \n\t" ) ;
                       
                        loadedSequences[nSequences].name = 
                            (char *) malloc( ( strlen(accession_id) + 1 ) * sizeof( char ) ) ;
                            
                       
                       strcpy(loadedSequences[nSequences].header, seqName) ;
                       
                        
                       strcpy( loadedSequences[nSequences].name , accession_id ) ; 
                        
                        // Collect the sequence from FASTA file                                             
                        
                        n = 0 ;
                                            
                        while ((c = getc(input)) != EOF)
                                    {
                                        if(c >= 'A' && c <= 'Z')
                                            {
                                                loadedSequences[nSequences].data[n++] = c ;
                                             
                                            }
                                    }  
                                   
                        
                        loadedSequences[nSequences].length = strlen((loadedSequences[nSequences].data)) ;
                        
                        fclose(input) ;
                        
                        ++nSequences ;
               
                    }
                    
///////////////// Write sequence in FASTA format //////////////////////////
               
                else if ((strcmp ( command, "write")) == 0 )
                    {
                        
                        list_num = atoi(strtok(NULL, " \n\t")) ;
                        filename = strtok(NULL, " \n\t") ;
                        output = fopen(filename, "w") ;
                        
                        fputs(loadedSequences[list_num].header, output) ;
                        fputs(loadedSequences[list_num].data, output) ;
                        
                        fclose(output) ;
                    }

what i am trying to do is take the data that was read in from a file and stored, and write out to a different file. the data is stored in loadedSequences[nSequences].data and loadedSequences[nSequences].header

There's nothing wrong with the fputs calls, provided the output file is opened and list_num is valid and there is data in the .header and .data strings. Are you sure that all those are true?

Thanks. My mistake was my index number. It should have been:

Code:

fputs(loadedSequences[list_num-1].header, output) ;
                        fputs(loadedSequences[list_num-1].data, output) ;

Appreciate the help