Joining these code snippets

Hi,

Im doing a project where I make a CSV reader in plain old C. Ive got some great code snippets through helpful users on the internet, but after experimenting I have found I have been unable to join the snippets into a working program.

Basic code structure

Code:

#include <stdio.h>

int main(int argc, char ** argv){
  int c;
  FILE * fp;

  if(argc < 2){
    printf("Usage:\n\t%s filename\n",argv[0]);
    return -1;
  }

  if((fp = fopen(argv[1],"rb")) == NULL){
    printf("can't open %s\n",argv[1]);
    return -2;
  }

  while((c = fgetc(fp)) != EOF){
    /* TO DO- Put your code to parse the csv here char by char
     */
    printf("%c",c);
  }

  fclose(fp);
  return 0;
}

This is my code that stores my CSV file contents and stores them in the memory:

Code:

#define MAX_LINE_LEN   1024*512  /* 1/2 mega byte, should be more than sufficient */
.....

    char line[MAX_LINE_LEN];
   int len=0;
   int cnt_of_fields=0;
   char *p;
   while( (c=GET_A_CHAR_FROM_FILE(fp))!=EOF){
           switch(c)
           {
           case '"':
           case '\'':
                    /* parse a quoted string, ignore it for now */
                  break; 
           case ',':
                  ++cnt_of_fields; /* a comma signal end of previous field and begining of next fields */
                  line[len++]='\0';
                  if(len==MAX_LINE_LEN){
                           fprintf(stderr, "Line too long\n");
                           exit(-1);
                  }             
                 break;
           case '\n':
                ++cnt_of_fields; /* a EOL is end of record, and at the same time end of field */
                  line[len++]='\0';
                  
                 /* make a copy of the line in the heap, note strdup or strcpy won't work in our case */
                p = (char *)malloc(len); 
                memcpy(p, line, len); /* now all the fields in the record are stored in p[ ] */ 
                add_a_record( p );
                break;
           default:
                line[len++] = c;
                  if(len==MAX_LINE_LEN){
                           fprintf(stderr, "Line too long\n");
                           exit(-1);
                  }             
           }
   }

This is my code that is designed to read the CSV data:

Code:

printf( "%s", line );

This is how I thought the completed code would look (It doesnt work)

Code:

#include <stdio.h>

int main(int argc, char ** argv){
  int c;
  FILE * fp;

  if(argc < 2){
    printf("Usage:\n\t%s filename\n",argv[0]);
    return -1;
  }

  if((fp = fopen(argv[1],"rb")) == NULL){
    printf("can't open %s\n",argv[1]);
    return -2;
  }

  while((c = fgetc(fp)) != EOF){
#define MAX_LINE_LEN   1024*512  /* 1/2 mega byte, should be more than sufficient */
.....

    char line[MAX_LINE_LEN];
   int len=0;
   int cnt_of_fields=0;
   char *p;
   while( (c=GET_A_CHAR_FROM_FILE(fp))!=EOF){
           switch(c)
           {
           case '"':
           case '\'':
                    /* parse a quoted string, ignore it for now */
                  break; 
           case ',':
                  ++cnt_of_fields; /* a comma signal end of previous field and begining of next fields */
                  line[len++]='\0';
                  if(len==MAX_LINE_LEN){
                           fprintf(stderr, "Line too long\n");
                           exit(-1);
                  }             
                 break;
           case '\n':
                ++cnt_of_fields; /* a EOL is end of record, and at the same time end of field */
                  line[len++]='\0';
                  
                 /* make a copy of the line in the heap, note strdup or strcpy won't work in our case */
                p = (char *)malloc(len); 
                memcpy(p, line, len); /* now all the fields in the record are stored in p[ ] */ 
                add_a_record( p );
                break;
           default:
                line[len++] = c;
                  if(len==MAX_LINE_LEN){
                           fprintf(stderr, "Line too long\n");
                           exit(-1);
                  }             
           }
   }
    printf( "%s", line );
  }

  fclose(fp);
  return 0;
}

you have 2 while loops one inside another

first is correct - so the second one should be probably removed as being wrong one

More like this?

Code:

#include <stdio.h>

int main(int argc, char ** argv){
  int c;
  FILE * fp;

  if(argc < 2){
    printf("Usage:\n\t%s filename\n",argv[0]);
    return -1;
  }

  if((fp = fopen(argv[1],"rb")) == NULL){
    printf("can't open %s\n",argv[1]);
    return -2;
  }

  while((c = fgetc(fp)) != EOF){
#define MAX_LINE_LEN   1024*512  /* 1/2 mega byte, should be more than sufficient */
.....

    char line[MAX_LINE_LEN];
   int len=0;
   int cnt_of_fields=0;
   char *p;
           switch(c)
           {
           case '"':
           case '\'':
                    /* parse a quoted string, ignore it for now */
                  break; 
           case ',':
                  ++cnt_of_fields; /* a comma signal end of previous field and begining of next fields */
                  line[len++]='\0';
                  if(len==MAX_LINE_LEN){
                           fprintf(stderr, "Line too long\n");
                           exit(-1);
                  }             
                 break;
           case '\n':
                ++cnt_of_fields; /* a EOL is end of record, and at the same time end of field */
                  line[len++]='\0';
                  
                 /* make a copy of the line in the heap, note strdup or strcpy won't work in our case */
                p = (char *)malloc(len); 
                memcpy(p, line, len); /* now all the fields in the record are stored in p[ ] */ 
                add_a_record( p );
                break;
           default:
                line[len++] = c;
                  if(len==MAX_LINE_LEN){
                           fprintf(stderr, "Line too long\n");
                           exit(-1);
                  }             
           }
   }
    printf( "%s", line );
  }

  fclose(fp);
  return 0;
}

the problem is - the most of your variables declared inside the loop should be initialized outside the loop - like len

so, obviosly, they should be declared outside the loop as well