Thread: How to store string

  1. #1
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    How to store string

    If the user enters a string, I want to store it, like if I want to store someone's name, how can I do that?

    I tried to write a program but I am having some warnings. What might be the correct way to store string?
    Code:
    #include<stdio.h>
    int main(void)
    {
     int i, size;
     
     char string [size];
     
     printf("Enter Size of string \n");
     
     scanf("%d",&size);
     
     printf(" Size of string : %d \n", size);
     
     for (int i = 0; i < size; i++)
     {
      scanf ("%c", &string[i]);
      printf ("%c", &string[i]);
     }
      
      return 0;
    }
    warning: format '%c' expects argument of type 'int', but argument 2 has type 'char *' [-Wformat=]
    printf ("%c", &string[i]);
    ^
    warning: unused variable 'i' [-Wunused-variable]
    int i, size;

  2. #2
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    Again, defining an array of variable length using an uninitialized 'size' is WRONG.
    And the warnings are correct.

  3. #3
    misoturbutc Hodor's Avatar
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    I hate VLAs even when they're done "right"

  4. #4
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    Quote Originally Posted by Hodor View Post
    I hate VLAs even when they're done "right"
    Me too... I prefer to allocate the buffer myself, in the heap, and keep the stack as short as possible.

  5. #5
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    I made two changes to remove the errors .

    Why size is being taken from the user , what purpose it is serving..?

    Code:
    #include<stdio.h>
    
    int main(void)
    {
     int i, size;
    
     char string [size];
    
     printf("Enter Size of string \n");
    
      scanf("%d",&size);
    
     printf(" Size of string : %d \n", size);
    
     for (i = 0; i < size; i++)
     {
      scanf ("%c", &string[i]);
      printf ("%c", string[i]);
     }
    
      return 0;
    }

  6. #6
    null pointer Structure's Avatar
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    Code:
    #include<stdio.h>
     
    int main(void) {
      printf("Enter Size of string \n");
      
      int size;
      scanf("%d",&size); 
      char string[size];
      
      printf(" Size of string : %d \n", size);
     
      for (int i = 0; i < size; i++) {
        printf( "%c", string[i] );
      }
      
      return 0;
    }
    "without goto we would be wtf'd"

  7. #7
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    Firstly, the program is wrong because size is an uninitialised non-const variable from which you are trying to create an array of characters. Neither does the programmer nor the computer know what size the array is. Technically, the computer does but forget about that because size is a variable holding some junk value and for all you know, it might be -29348 or something. Your compiler will flag that as an issue as long as you haven't suppressed warnings. Don't create arrays of unknown length.

    Secondly, think for a minute why you may need to know the size from the user. Let's say you need to maintain a record of names. Every name doesn't have the same size. So, in practice, you allot a fixed size and tell the user that "max size you can enter is X".

    Thirdly, you should be creating variable length arrays dynamically instead statically.

    Fourthly, what you need is a good C/C++ book that explains all of this step by step.
    "Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning." - Rick Cook, The Wizardry Compiled

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