#assign char array by loop, then out output in order by loop

54 messages · Page 1 of 1 (latest)

ember vine
# 

            int i;
            int i2;


            printf("enter char array amount\n");
            scanf("%d",&i);

            char char1[i];

            char1[0] = 'A';

            for(i2=0;i2<i;i2++){
                char1[i] = char1[i-1]++;
            }


            for(i2=0;i2<i;i2++){
                printf("%c\n",char1[i2]);
            }
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#

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ember vine
#

a bit confused so far

pulsar trench
#

considering char1[i] = char1[i-1]++; is UB - so am i

#

what are you trying to do exactly?

ember vine
#

so, to input number,

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then output from A to x depending on input

#

so if 7 is entered
output:
A
B
C
D
E
F
G

pulsar trench
#

do you have to use an array for that? why don't you just print it one char at a time?

ember vine
#

i could, but the array version is more compact, its part of the excercise

pulsar trench
#

is more compact
its most certainly not, but given its an exercise - it doesn't really matter

#

regardless (assuming you're fine with VLAs) - consider the value of i in this loop

for(i2=0;i2<i;i2++){
  char1[i] = char1[i-1]++;  // whats the value of i here?
}```
ember vine
#

0

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shold be 1 i think

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because [0] is already A

pulsar trench
#

no. its whatever your user supplied you with

pulsar trench
# 
int i;
printf("enter char array amount\n");
scanf("%d", &i);

char char1[i];  // VLA

...

for(int j = 0; j < i; j++){
    char1[i] = char1[i-1]++;
}```
does this makes it clearer?
#

j and i are 2 different variables. i was never changed (i.e. its equal to the last index of the array + 1) yet the loop uses i to access the array for some reason

ember vine
#

i get the loop

#

its just the

pulsar trench
#

no. its not

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at this point i suggest you run through that snippet with either a pen & paper / through a debugger and see what is the value of i throught the iteration

ember vine
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char1[1] = char1[1]+ char1[-1];

#

which is sopposed to set to 'B', but it makes it a 'Y' instead

pulsar trench
#

thats still UB. you're not allowed to access char[-1]

pulsar trench
ember vine
#

its assign array[1], not [0]

#

[0] is automatically a A from the coding

pulsar trench
#

and after you've done that - i suggest you first figure out how to print the chars rather than storing them in the array first

ember vine
#

ok

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char1[0] = 'A';
done

pulsar trench
ember vine
#

char1[0]++;

changed from A to B

#

so how would you make array[0] (which is A) an array[1] to a B

pulsar trench
#

i would use the correct index in a loop

ember vine
#

ye you need the correct loop, also you need the assignment within the loop

pulsar trench
#

sure. compare this loop to yours

for(size_t i = 0; i < size; i ++) {
  arr[i] = 'A' + ...;
}```
ember vine
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so, this works

char1[1] = char1[0]++;

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assigns B from A

pulsar trench
#

sure. i suggest you won't do it that way. refer to my loop above

ember vine
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k

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whats the . . .

pulsar trench
#

its a value you need to figure out

ember vine
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A + 1?

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A + loop int?

pulsar trench
#

are you just guessing?

ember vine
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no

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i guess

the loop

A + x(1) = B
A + x(2) = C

could work

ember vine
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ive figured it out

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how do i show the code on here?

# 
            int i2;


            printf("enter char array amount\n");
            scanf("%d",&i2);

            char char1[i2];

            char1[0] = 'A';


            for(i=1;i<i2;i++){
                char1[i] = (char1[i-1])+1;
            }

            for(i=0;i<i2;i++){
                printf("%c\n",char1[i]);
            }```
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#

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ember vine
#

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