C language beginners' doubts, no, require recursion

#include <stdio.h>int cnt=0;void comb(int a[],int m,int k,int s) {    int i,j,t;    for(i=m;i>=k;i--)    {        a[k]=i;        if(k>1)            comb(a,i-1,k-1,s);        else        {            for(t=0,j=a[0];j>0;j--)                t=t+a[j];                        if(t==s)            {                cnt++;                printf("%d=", s);                for(j=a[0];j>1;j--)                printf("%d+", a[j]);                printf("%d\n", a[1]);            }        }    }}int main(){    int a[100],s,m,i;    while (1)    {        scanf("%d %d", &s, &m);        if (s == 0)        {            break;        }                cnt=0;        for (i=1;i<=m;i++)        {            a[0]=i;            comb(a,m,i,s);        }            printf("%d\n", cnt);    }    return 0;}

Running results ：

“ Given a small point of input , Full single step tracking ( Press at the same time Alt+7 Key view Call Stack The corresponding function call history from the inner layer to the outer layer is listed from top to bottom ) Again .” Is the only way to understand the working principle of recursive functions ！
Recursive functions focus on the following factors
· Exit conditions
· What are the parameters
· What is the return value
· What are the local variables
· What are the global variables
· When to output
· Will it cause stack overflow

For reference only ：

#include <stdio.h>#include <stdlib.h>void print(int res[], int num) {    static int L=0;    L++;    printf("%8d:",L);    for (int i=0;i<num;++i) {        printf(" %d", res[i]);    }    printf("\n");}void split(int n, int m) {
   
   
   
   // n Represents the total number ,m Represents the maximum factor     static int res[100];//  Save results     static int num=-1;//  Current factor subscript     if (n<m || n<0 || m<1) return;    num++;    if (0==n) {
   
   
   
   //  Recursive termination condition , by 0 Can not be further divided , Direct output         print(res,num+1);        num--;        return;    } else {        if (n==m) {
   
   
   
   //  Don't dismantle , Direct output             res[num]=m;            print(res,num+1);            num--;        } else {            //  Split the first             res[num]=m;            n=n-m;            if (m>n) m = n; //  The maximum factor cannot be greater than the total             for (int i=m;i>=1;--i) {
   
   
   
   //  loop , The second factor can continue to split , And it can be divided into multiple according to the maximum factor                 split(n,i);            }            num--;        }    }}void Split(int n) {    if (n<=0) return;    if (100<n) {        printf("Up to 100\n");        return;    }    for (int i=n;i>=1;--i) {        split(n, i);    }}void main(int argc,char **argv) {         if (argc<=1) Split(5);    else if (argc>=3) split(atoi(argv[1]),atoi(argv[2]));    else              Split(atoi(argv[1]));}