CODEWITHSUNDEEP
cstring
Hafiz Temuri
Hafiz Temuri

Reputation: 4112

Multiple Lines Input in C - Troubleshooting

I am trying to read multiple line inputs in c. Very first input that I enter gets print out completely fine, but the rest of them are missing the first character.

So, I am trying to print if the entered name(string) is a valid identifier name or not, and I want to get the inputs in an endless loop. I know there are many similar questions are already posted here, but none of them are working for me. I am not sure what I am doing wrong here. :(

int main() {
        char str[1000];

        for(;;){
                //Below, I have tried every possibility that I can think of
                scanf("%[^\n]d%*c%*s", str);
                //fgets(str, 1000, stdin);
                printf("str[0]: %c\n", str[0]);

                //Flushing the Buffer    
                while ( (dump = getchar()) == '\n' && dump != EOF);
                //fflush(stdout);
        }
}

I am putting my whole code, just for in case,

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

int main() {
        char str[1000];
        int i, dump, check;

        for(;;){
                check = 0;
                scanf("%[^\n]d%*c%*s", str);
                //fgets(str, 1000, stdin);
                printf("str[0]: %c\n", str[0]);
                if ( (str[0] == '_') || ( isalpha(str[0]) ) ){
                        for (i = 1; i < strlen(str); i++) {
                                if (isalpha(str[i]) || isdigit(str[i])) {
                                        continue;
                                } else{
                                        printf("2Invalid\n");
                                        check = 1;
                                }
                        }
                        if (check != 1){
                                printf("String: %s\n", str);
                                printf("Valid\n");
                        }
                } else{
                        printf("Invalid\n");
                        break;
                }

                //Flushing the Buffer    
                while ( (dump = getchar()) == '\n' && dump != EOF);
                //fflush(stdout);
        }
}

Input: asdasffa Output: str[0]: a String: asdasffa Valid

Input: &asdaf Output: str[0]: a (when str[0] is "&", not "a") String: asdaf Valid

Input: %asdf Output: str[0]: a (when str[0] is "%", not "a") String: asdf Valid

I am guessing the way I am flushing the buffer causing this problem?

Thanks!

Upvotes: 0

Views: 138

Answers (1)

William Pursell
William Pursell

Reputation: 212208

The line while ( (dump = getchar()) == '\n' && dump != EOF); consumes a character. Try adding a call to ungetc after this so the scanf can see it. And remove the redundant dump != EOF. If dump == \n, then it won't be EOF.

Upvotes: 2

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