Write a program that says how many times it was ran [duplicate]

Question

Write a program that after running will show how many times it was ran before. You are only allowed to modify the executable itself (the code itself, or compiled version of your code), you cannot modify anything else or create new files.

Example:

$ ./yourprogram
0
$ ./yourprogram
1
$ ./yourprogram
2

Answer 1

Somewhat less trivial example than y'old bash, in C:

#include <stdio.h>

int main(int argc,char **argv){
    const char *data="Da best marker in da world 0\0\0\0\0\0\0";
    FILE *f;
    int i;
    char c;
    long int pos;
    printf("%s\n",data+27);
    f=fopen(argv[0],"r+b");
    i=0;
    c=fgetc(f);
    while(!feof(f)){
        if(data[i]==c){
            i++;
            if(i==27)break;
        } else i=0;
        c=fgetc(f);
    }
    if(i!=27)return 1;
    i=0;
    pos=ftell(f);
    c=fgetc(f);
    while(c!='\0'){
        i=10*i+c-'0';
        c=fgetc(f);
    }
    i++; //The increment!
    fseek(f,pos,SEEK_SET);
    fprintf(f,"%d",i);
    fflush(f);
    fclose(f);
    return 0;
}