isnumber function
==============
check before atoi,atof the string you want to convert

Code:
#include <stdio.h>
#include <ctype.h>
#include <string.h>


int isNumber(char []);

int isNumber(char text[]){
int isit=1;
    for(int i=0;i<strlen(text);i++){
        if (!isdigit(text[i])){
            isit=0;
            break;
        }
    }
return isit;
}

int main (){
  char str1[]="1g776ad";
  char str2[]="1776d"; 
  char str3[]="g1776"; 
  char str4[]="1776"; 
  printf("\n<1=true , 0=false> isnumber=%d",isNumber(str1));
  printf("\n<1=true , 0=false> isnumber=%d",isNumber(str2));
  printf("\n<1=true , 0=false> isnumber=%d",isNumber(str3));
  printf("\n<1=true , 0=false> isnumber=%d",isNumber(str4));
  getchar();
  return 0;
}