execution - Adding an additional printf line affects C code -

i adding simple printf line in code , affects whether line before executed or not. restarted terminal it's still same. tried on online compiler , executor , there's no problem, in computer have problem. restarting pc doesn't help.

else     {         lf++;     } 

when put lf not increased , program outputs "0 strings" on pc, "4 strings" on http://www.tutorialspoint.com/compile_c_online.php

when replace with

else     {         lf++;         printf("\ndo here?\n");     } 

it outputs "4 strings" in both platforms (as should). can reason behind this? far know simple printf shouldn't affect whether line before executed or not, independent c compiler use.

here original code:

#include"mylib.h" #define max 67108863 char tab[100][27]; double val[100]; int l;  void showtab(file *fout) {     int i, j;     printf("\nnumber of strings %d\n",l);     for(i=0;i<l;i++)     {         fprintf(fout,"%lf ",val[i]);         for(j=0;j<26;j++)         {             if(tab[i][j])                 fputc('a'+j,fout);                   }         fprintf(fout,"\n");     } }  int find(char*s, int stl) {     int i, j, b=1;     for(i=0;i<l;i++)     {         if(tab[i][26]!=stl)             continue;         for(j=0;j<stl;j++)         {             if(tab[i][s[j]-'a']!=1)             {                 b=0;                 break;             }         }         if(b==0)         {             b=1;             continue;         }         return i;     }     return -1; }  void clean() {     int i, j, k, lf=0;     for(i=0;i<l-1 && j<l;i++)     {         if(j<=i)             j=i+1;         if(val[i]==0)         {             while(j<l)             {                 if(val[j]!=0)                 {                     for(k=0;k<27;k++)                         tab[i][k]=tab[j][k];                     val[i]=val[j];                     val[j]=0;                     j++;                     lf++;                     break;                 }                 j++;             }         }         else         {             lf++;         }     }     l=lf;     return; }  int main() {     char s[26], b=1, inequ;     int adr, stl, i;     double v;     file* fin=fopen("data","r");     file* fout=fopen("canonical.form","w");     l=0;     while(b)     {         fscanf(fin,"%s",s);         if(s[0]!='<' && s[0]!='>')         {             fscanf(fin,"%lf",&v);             stl=strlen(s);             adr=find(s,stl);             if(adr==-1)             {                 for(i=0;i<26;i++)                     tab[l][i]=0;                 for(i=0;i<stl;i++)                     tab[l][s[i]-'a']=1;                 tab[l][26]=stl;                 val[l]=v;                 l++;             }             else                 val[adr]+=v;         }         else         {             if(s[0]=='<')                 inequ=-1;             else                 inequ=1;             b=0;         }     }     while(fscanf(fin,"%s %lf",s,&v)==2)     {         stl=strlen(s);         adr=find(s,stl);         if(adr==-1)         {             for(i=0;i<26;i++)                 tab[l][i]=0;             for(i=0;i<stl;i++)                 tab[l][s[i]-'a']=1;             val[l]=-v;             l++;         }         else             val[adr]-=v;     }     clean();     if(inequ==-1)         fprintf(fout,"0>=\n");     else         fprintf(fout,"0<=\n");     showtab(fout);      return 0; } 

i don't use defined in mylib.h in piece of code except

#include<stdio.h> #include<stdlib.h> #include<string.h> 

and here input file:

az 1.000000 z -1.000000 bz 1.000000 z -1.000000 abz -1.000000 z 1.000000 ab 1.000000 z 1.000000 abz -1.000000 -1.000000 b -1.000000 ab 1.000000 <= ab 1.000000 b -1.000000 zb 1.000000 b -1.000000 azb -1.000000 b 1.000000 ba 1.000000 -1.000000 za 1.000000 -1.000000 bza -1.000000 1.000000 xyab 3.000000 ab -3.000000 zab 3.000000 ab -3.000000 xyzab -3.000000 ab 3.000000 

you don't initialize variables before using them invoke undefined behavior.

you need set j, k etc zero.