how to prevent user from entering char when needing int in c

// return -1 on EOF int GetPositiveNumber(const char *prompt, const char *reprompt) { char buf[100]; fputs(prompt, stdout); fflush(stdout); while (fgets(buf, sizeof buf, stdin)) [ int value; if (sscanf(buf, "%d", &value) == 1 && value > 0) { return value; } fputs(reprompt, stdout); fflush(stdout); } return -1; } // Usage int TktAdult = GetPositiveNumber( "nEnter amount of adult tickets:" , "nPlease enter a positive number!"); if (TktAdult < 0) Handle_End_of_File(); else Success(TktAdult);

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

int main()
{
    int i=0, isFloat=0, isChar=0;
    int intNum=0;
    float floatNum=0;
    char str[100];
    printf("Enter a number:");
    scanf("%s",str); // no &
    for(i=0; i<strlen(str); ++i)
    {
        // if not 0-9
        if(!((str[i]>='0')&&(str[i]<='9')))
        {
            if(str[i]=='.')
            {
                isFloat ++;
            }
            else{
                isChar ++;
            }
        }
    }
     if(isChar || isFloat > 1)
     {
         printf("This is not a number.");
     }
     else if(isFloat == 1)
     {
         printf("This is a float.");
         floatNum=atof(str);
         printf("input as float %.2fn",floatNum);
     }
     else {
         printf("This is a valid int.n");
         intNum=atoi(str);
         printf("input as int %dn",intNum);
     }
    return 0;
}

Posted by: Guest on February-04-2022

#include <stdio.h> int main() { int num=1; int numberRead = 0; do{ printf("Enter a number: "); numberRead = scanf("%d",&num); while(numberRead != 1){ printf("That is not a number.n"); scanf("%*[^n]"); //or fflush(stdin); printf("Enter a number: "); numberRead = scanf("%d",&num); } printf("You entered %dn",num); }while(num != 0); return 0; }

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