C - Split string with repeated delimiter char into 2 substrings












0















I'm making a very simple C program that simulates the export command, getting an input with fgets().



Input example:




KEY=VALUE




Has to be converted to:



setenv("KEY", "VALUE", 1);


That's easy to solve with something similar to this code:



key = strtok(aux, "=");

value = strtok(NULL, "=");


The problem comes when the user input a value that start with one or several equals = characters. For example:




KEY===VALUE




This should be converted to:



setenv("KEY", "==VALUE", 1);


But with my current code it is converted to:



setenv("KEY", NULL, 1);


How I can solve this?



Thanks in advice.






c strtok







share|improve this question

























  • You have to write your own parser.

    – john elemans
    Nov 13 '18 at 19:11






  • 4





    You could just use strchr instead of strtok

    – Andrew Sun
    Nov 13 '18 at 19:11











  • Can't reproduce. coliru.stacked-crooked.com/a/913d3de1fdad058a

    – SergeyA
    Nov 13 '18 at 19:13
















0















I'm making a very simple C program that simulates the export command, getting an input with fgets().



Input example:




KEY=VALUE




Has to be converted to:



setenv("KEY", "VALUE", 1);


That's easy to solve with something similar to this code:



key = strtok(aux, "=");

value = strtok(NULL, "=");


The problem comes when the user input a value that start with one or several equals = characters. For example:




KEY===VALUE




This should be converted to:



setenv("KEY", "==VALUE", 1);


But with my current code it is converted to:



setenv("KEY", NULL, 1);


How I can solve this?



Thanks in advice.






c strtok







share|improve this question

























  • You have to write your own parser.

    – john elemans
    Nov 13 '18 at 19:11






  • 4





    You could just use strchr instead of strtok

    – Andrew Sun
    Nov 13 '18 at 19:11











  • Can't reproduce. coliru.stacked-crooked.com/a/913d3de1fdad058a

    – SergeyA
    Nov 13 '18 at 19:13














0












0








0








I'm making a very simple C program that simulates the export command, getting an input with fgets().



Input example:




KEY=VALUE




Has to be converted to:



setenv("KEY", "VALUE", 1);


That's easy to solve with something similar to this code:



key = strtok(aux, "=");

value = strtok(NULL, "=");


The problem comes when the user input a value that start with one or several equals = characters. For example:




KEY===VALUE




This should be converted to:



setenv("KEY", "==VALUE", 1);


But with my current code it is converted to:



setenv("KEY", NULL, 1);


How I can solve this?



Thanks in advice.






c strtok







share|improve this question
















I'm making a very simple C program that simulates the export command, getting an input with fgets().



Input example:




KEY=VALUE




Has to be converted to:



setenv("KEY", "VALUE", 1);


That's easy to solve with something similar to this code:



key = strtok(aux, "=");

value = strtok(NULL, "=");


The problem comes when the user input a value that start with one or several equals = characters. For example:




KEY===VALUE




This should be converted to:



setenv("KEY", "==VALUE", 1);


But with my current code it is converted to:



setenv("KEY", NULL, 1);


How I can solve this?



Thanks in advice.






c strtok




c strtok






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 13 '18 at 19:07







Tony Ceralva

















asked Nov 13 '18 at 19:05









Tony CeralvaTony Ceralva

7471720




7471720













  • You have to write your own parser.

    – john elemans
    Nov 13 '18 at 19:11






  • 4





    You could just use strchr instead of strtok

    – Andrew Sun
    Nov 13 '18 at 19:11











  • Can't reproduce. coliru.stacked-crooked.com/a/913d3de1fdad058a

    – SergeyA
    Nov 13 '18 at 19:13



















  • You have to write your own parser.

    – john elemans
    Nov 13 '18 at 19:11






  • 4





    You could just use strchr instead of strtok

    – Andrew Sun
    Nov 13 '18 at 19:11











  • Can't reproduce. coliru.stacked-crooked.com/a/913d3de1fdad058a

    – SergeyA
    Nov 13 '18 at 19:13

















You have to write your own parser.

– john elemans
Nov 13 '18 at 19:11





You have to write your own parser.

– john elemans
Nov 13 '18 at 19:11




4




4





You could just use strchr instead of strtok

– Andrew Sun
Nov 13 '18 at 19:11





You could just use strchr instead of strtok

– Andrew Sun
Nov 13 '18 at 19:11













Can't reproduce. coliru.stacked-crooked.com/a/913d3de1fdad058a

– SergeyA
Nov 13 '18 at 19:13





Can't reproduce. coliru.stacked-crooked.com/a/913d3de1fdad058a

– SergeyA
Nov 13 '18 at 19:13












2 Answers
2






active

oldest

votes


















3














Your second strtok() should not use = as the delimiter. You would only do that if there were another = that ended the value. But the value ends at the end of the string. Use an empty delimiter for this part.



key = strtok(aux, "=");

value = strtok(NULL, "");





share|improve this answer
























  • Thanks! It works prefectly.

    – Tony Ceralva
    Nov 13 '18 at 19:43



















0














strtok is probably overkill (and non-reentrant) when it's just one token. This will do,



#include <stdlib.h>

#include <stdio.h>

#include <string.h>



int main(int argc, char **argv) {

    char *key, *equals, *value;

    if(argc != 2 || !(equals = strchr(key = argv[1], '=')))

       return fprintf(stderr, "KEY=VALUEn"), EXIT_FAILURE;

    value = equals + 1;

    *equals = '';

    printf("key: <%s>; value: <%s>.n", key, value);

    return EXIT_SUCCESS;

}


Although strtok is probably easier to read. One may try strsep, but it is GNU C.






share|improve this answer























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    2 Answers
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    active

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    3














    Your second strtok() should not use = as the delimiter. You would only do that if there were another = that ended the value. But the value ends at the end of the string. Use an empty delimiter for this part.



    key = strtok(aux, "=");
    
value = strtok(NULL, "");





    share|improve this answer
























    • Thanks! It works prefectly.

      – Tony Ceralva
      Nov 13 '18 at 19:43
















    3














    Your second strtok() should not use = as the delimiter. You would only do that if there were another = that ended the value. But the value ends at the end of the string. Use an empty delimiter for this part.



    key = strtok(aux, "=");
    
value = strtok(NULL, "");





    share|improve this answer
























    • Thanks! It works prefectly.

      – Tony Ceralva
      Nov 13 '18 at 19:43














    3












    3








    3







    Your second strtok() should not use = as the delimiter. You would only do that if there were another = that ended the value. But the value ends at the end of the string. Use an empty delimiter for this part.



    key = strtok(aux, "=");
    
value = strtok(NULL, "");





    share|improve this answer













    Your second strtok() should not use = as the delimiter. You would only do that if there were another = that ended the value. But the value ends at the end of the string. Use an empty delimiter for this part.



    key = strtok(aux, "=");
    
value = strtok(NULL, "");






    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered Nov 13 '18 at 19:24









    BarmarBarmar

    423k35244346




    423k35244346













    • Thanks! It works prefectly.

      – Tony Ceralva
      Nov 13 '18 at 19:43



















    • Thanks! It works prefectly.

      – Tony Ceralva
      Nov 13 '18 at 19:43

















    Thanks! It works prefectly.

    – Tony Ceralva
    Nov 13 '18 at 19:43





    Thanks! It works prefectly.

    – Tony Ceralva
    Nov 13 '18 at 19:43













    0














    strtok is probably overkill (and non-reentrant) when it's just one token. This will do,



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

    
int main(int argc, char **argv) {
    
    char *key, *equals, *value;
    
    if(argc != 2 || !(equals = strchr(key = argv[1], '=')))
    
       return fprintf(stderr, "KEY=VALUEn"), EXIT_FAILURE;
    
    value = equals + 1;
    
    *equals = '';
    
    printf("key: <%s>; value: <%s>.n", key, value);
    
    return EXIT_SUCCESS;
    
}


    Although strtok is probably easier to read. One may try strsep, but it is GNU C.






    share|improve this answer




























      0














      strtok is probably overkill (and non-reentrant) when it's just one token. This will do,



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

      
int main(int argc, char **argv) {
      
    char *key, *equals, *value;
      
    if(argc != 2 || !(equals = strchr(key = argv[1], '=')))
      
       return fprintf(stderr, "KEY=VALUEn"), EXIT_FAILURE;
      
    value = equals + 1;
      
    *equals = '';
      
    printf("key: <%s>; value: <%s>.n", key, value);
      
    return EXIT_SUCCESS;
      
}


      Although strtok is probably easier to read. One may try strsep, but it is GNU C.






      share|improve this answer


























        0












        0








        0







        strtok is probably overkill (and non-reentrant) when it's just one token. This will do,



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

        
int main(int argc, char **argv) {
        
    char *key, *equals, *value;
        
    if(argc != 2 || !(equals = strchr(key = argv[1], '=')))
        
       return fprintf(stderr, "KEY=VALUEn"), EXIT_FAILURE;
        
    value = equals + 1;
        
    *equals = '';
        
    printf("key: <%s>; value: <%s>.n", key, value);
        
    return EXIT_SUCCESS;
        
}


        Although strtok is probably easier to read. One may try strsep, but it is GNU C.






        share|improve this answer













        strtok is probably overkill (and non-reentrant) when it's just one token. This will do,



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

        
int main(int argc, char **argv) {
        
    char *key, *equals, *value;
        
    if(argc != 2 || !(equals = strchr(key = argv[1], '=')))
        
       return fprintf(stderr, "KEY=VALUEn"), EXIT_FAILURE;
        
    value = equals + 1;
        
    *equals = '';
        
    printf("key: <%s>; value: <%s>.n", key, value);
        
    return EXIT_SUCCESS;
        
}


        Although strtok is probably easier to read. One may try strsep, but it is GNU C.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 13 '18 at 19:44









        Neil EdelmanNeil Edelman

        42228




        42228






























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