finding letters in a string..

This function gets a sequence in string and return 1 if all the letters in the string are
comprised of capitalized ACGT. At the last place of the string there is ‘\0’. In case there is
a char which is not ACGT in the string, the function returns 0.

Code:

int isLegitSequence(char sequence[])
{
    int i = 0, j;

    while(sequence[i] != '\0')
	{
        i++;
    }

    for (j = (i-1) ; j >= 0 ; j--)
	{
        if((sequence[j] != 'A') || (sequence[j] != 'G') || (sequence[j] != 'C') || (sequence[j] != 'T'))
		{
            return 0;
        }
    }
	return 1;
}

 

if you mean something like like "does AGCT exist in this string?" then couldn't you just use strstr?

Code:

int isLegitSequence(char *sequence, char *pattern) {

   return (strstr(sequence, pattern) != NULL ? 1 : 0);
}

 

no the string can only be with those capitallized chars 'A', 'C', 'G' or 'T'....