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Top Forums Programming Map with struct as key and vector as value Post 302917587 by Corona688 on Wednesday 17th of September 2014 03:54:24 PM
Old 09-17-2014
Your program is a mess, had no error checking and crashed nonstop. That's why strtok is considered "evil" -- if you don't bother checking, bad things will happen. But a little checking makes it fine.

Nearly every line ended up commented out and replaced, I had to rewrite it instead.

Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>     // You need this for atoi, see 'man atoi'

#include <map>
#include <vector>
#include <string>
using namespace std;

struct grades {
    string course_Abrrev;
    int course_Credit;
    char course_Grade;
};

int main(void)
{
        char buf[4096];
        map<int, string> names;
        map<int, vector < grades > > marks;

        // Read a line into 'buf'
        while(fgets(buf, 4096, stdin) != NULL)
        {
                // Array of 10 pointers.
                // Each will point to a position inside 'buf', or
                // just point to "".
                const char *token[10];
                grades grade;
                int n=0;

                token[n]=strtok(buf, " \r\n\t");
                while(n < 10)
                {
                        n++;
                        token[n]=strtok(NULL, " \r\n\t");
                        if(token[n]==NULL) break;
                }
                // Set all NULL strings to "" instead.
                while(n < 10) token[n++]="";

                // There, now we have a nice array of tokens
                // which are all guaranteed not to crash when used.
                // The very worst any of them will be is blank...

                n=atoi(token[0]);       // Get student ID

                grade.course_Abrrev=token[2];
                grade.course_Credit=atoi(token[3]);
                grade.course_Grade=*(token[3]);

                names[n]=token[1];              // Store name
                marks[n].push_back(grade);      // store grade
        }

        for(map<int, string>::iterator i=names.begin();
                i != names.end();
                i++)
        {
                int id=(*i).first;
                printf("%d %s\n", id, (*i).second.c_str());

                for(vector<grades>::iterator n=marks[id].begin();
                        n != marks[id].end();
                        n ++ )
                {
                        printf("\t%s %d %c\n",
                                (*n).course_Abrrev.c_str(),
                                (*n).course_Credit,
                                (*n).course_Grade);
                }

        }
}

This User Gave Thanks to Corona688 For This Post:
 

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STRSEP(3)						     Linux Programmer's Manual							 STRSEP(3)

NAME
strsep - extract token from string SYNOPSIS
#include <string.h> char *strsep(char **stringp, const char *delim); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): strsep(): _BSD_SOURCE DESCRIPTION
If *stringp is NULL, the strsep() function returns NULL and does nothing else. Otherwise, this function finds the first token in the string *stringp, where tokens are delimited by symbols in the string delim. This token is terminated by overwriting the delimiter with a null byte ('') and *stringp is updated to point past the token. In case no delimiter was found, the token is taken to be the entire string *stringp, and *stringp is made NULL. RETURN VALUE
The strsep() function returns a pointer to the token, that is, it returns the original value of *stringp. CONFORMING TO
4.4BSD. NOTES
The strsep() function was introduced as a replacement for strtok(3), since the latter cannot handle empty fields. However, strtok(3) con- forms to C89/C99 and hence is more portable. BUGS
Be cautious when using this function. If you do use it, note that: * This function modifies its first argument. * This function cannot be used on constant strings. * The identity of the delimiting character is lost. SEE ALSO
index(3), memchr(3), rindex(3), strchr(3), string(3), strpbrk(3), strspn(3), strstr(3), strtok(3) COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. GNU
2011-09-28 STRSEP(3)
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