recursion - Getting help recursive C programming -

given array of length n, , requirement write program calculate number of sub-sequences of length m of given array.

below code it. please, have look.

int reccountsubseq(int seqlength, int length, int s[]) {     int answer;      if (seqlength == 0) {       /* base case: found subseq of correct length */         return 1;     }      if (seqlength >= length) {  /* base case: possible seqlength == length*/         return (seqlength==length);     }      /* recursive case: 2 branches */     answer = reccountsubseq(seqlength-1, length-1, s); /* s[length-1] in subseq*/     printf("answer=%d\n", answer);      answer += reccountsubseq(seqlength, length-1, s);  /* s[length-1] not in subseq */     printf("increased answer %d\n", answer);      return answer; }  void countsubseq(int seqlength, int length, int s[]) {         printf("#subseq = %d\n", reccountsubseq(seqlength, length, s));     }  int main() {     int length;     scanf("%d", &length);      int seqlength;     int i;     int s[100];      (i=0;i<length; i++) {         scanf("%d", &s[i]);     }      countsubseq(seqlength, length, s);      return 0; } 

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now, my question: why value of seqlength decreasing each time, , how code working ?

the function has undefined behaviour because @ least variable seqlength not initialized:

int seqlength; 

and task not clear. if have array n elements number of continious subsequencies of length m m <= n equal n - m + 1.

so writing such function not make great sense.:) not see in function there access array passed third argument.:)

insetad can suggest following function. @ least has sense.:)

#include <stdio.h>  size_t reccountsubseq( const int a[], size_t n, size_t m ) {     if ( m <= n )     {         ( size_t = 0; < m; i++ ) printf( "%d ", a[i] );         printf( "\n" );     }      return n <= m ? n == m : 1 + reccountsubseq( ++a, --n, m ); }  int main( void ) {     int a[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };      printf( "there %zu subsequencies\n", reccountsubseq( a, sizeof( ) / sizeof( *a ), 3 ) );      return 0; } 

its output is

1 2 3  2 3 4  3 4 5  4 5 6  5 6 7  6 7 8  7 8 9  there 7 subsequencies 

i think incorrectly interpretating assignment , solution. should check descriptions anew.