הפתרון שלי לשאלה הראשונה: (יש פתרונות אלגנטים יותר באינטרנט, פשוט חפשו c itoa implementation) #include <stdlib.h> #include <stdio.h> // Returns the length of an integer int howLong(int value){ int tens = 10; int mod = 0; int i = 0; do{ mod = value%tens; i++; tens *= 10; }while(mod != value); return i; } // itoa implementation void itoa2(int value, char* str){ int start = 0; int end = 0; int length = howLong(value); if(value<0){ *(str) = '-'; start = 1; end = 1; } int currentDigit = 0; int tens = 10; for(int i=(length + end) - 1;i>=start;i--){ /* Take the modulo of the current multiplicity of 10 minus the previous one and divide the result by the previous multiplicity of 10 */ currentDigit = (tens == 10)?(abs(value) % tens):(((abs(value) % tens) - (abs(value) % (tens / 10))) / (tens / 10)); switch(currentDigit){ case 0: *(str + i) = '0'; break; case 1: *(str + i) = '1'; break; case 2: *(str + i) = '2'; break; case 3: *(str + i) = '3'; break; case 4: *(str + i) = '4'; break; case 5: *(str + i) = '5'; break; case 6: *(str + i) = '6'; break; case 7: *(str + i) = '7'; break; case 8: *(str + i) = '8'; break; case 9: *(str + i) = '9'; break; } tens *= 10; } *(str + length + end) = '\0'; } // Returns absolute number int abs(int value){ if(value<0) return value*(-1); return value; } void main(){ int value= -1234; char *str; str= (char*)malloc(100); itoa2(value1, str); flushall(); puts(str); free(str); }