s期望使用char c类型的参数，但是参数2具有类型'int'的警告和错误的返回值

Question

Yes ,I know that this question was already asked for many times ,but none of these helped me to discover the problem (duplicate...yeah). I want to read from input a series of strings into an array and then search from 'First Name'. If the name exist ,I want to display all the data stored in that element of array (I attached the code to undestand easily). When I run it ,I read from keyboard all the data ,but it returns me absolutely nothing.

#include<stdio.h>

typedef struct record {
    char name[10],lname[10],phone[10],bday[10];
};
void main() {
 struct record rec;
 char search;
 int i,nr;

printf("\nInput number of records: ");
scanf("%d",&nr);

for (i=0 ; i<nr ;i++) {
    printf("First name: ");
    scanf("%s",&rec.name[i]);
    printf("Last name: ");
    scanf("%s",&rec.lname[i]);
    printf("Phone: ");
    scanf("%s",&rec.phone[i]);
    printf("Bday: ");
    scanf("%s",&rec.bday[i]);
}

printf("Input the first name for searching: ");
scanf("%s",&search);

for (i=0 ;i<nr;i++) {
    if (search == rec.name[i]) {
        printf("First name: %s\nLast name: %s\nPhone: %s\nB-day: %s",rec.name[i],rec.lname[i],rec.phone[i],rec.bday[i]);
    } 
}

}

NOTE: I already replaced

scanf("%s",&rec.name[i]); 

with

scanf("%s",rec.name[i]);

but no effect.

Answer 1

I believe there are a lot of problems with your code.

Firstly in this line:

scanf("%s",&search);

You have declared search as only a char , when really you want an array of chars. You also don't need & with search , as an array decays to a pointer to the first element.

It instead should be like this:

char search[10];
scanf("%9s", search); /* %9s to avoid buffer overflow */

You need to make this change to all your other scanf() calls, as this seems to be everywhere in this code.

It also seems that you want to create an array of records(structures), So you might need to make this after getting the value of nr . You can create it like this:

struct record rec[nr]; /* array of nr structures */

This also means calls like this:

rec.name[i]

Don't make sense, as you are iterating over the characters within a name, not over all the records in struct records .

This needs to be instead:

rec[i].name

Secondly, Your using == to compare strings, when you should be using strcmp instead. Using == will only compare the base address of the strings, not the actual contents of strings.

Your line should be this instead:

if (strcmp(search, rec[i].name) == 0) { 

If you read the manual page for strcmp() , checking for a return value of 0 means that both strings are equal in comparison.

Lastly, in your first scanf() call:

scanf("%d",&nr);

You should really check the return value of this:

if (scanf("%d", &nr) != 1) {
    /* exit program */
}

Note: For reading strings, you should really be using fgets instead. You can try upgrading to this later, but I think it is better to understand these basics first.

Here is working example of what your program should do:

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

#define STRSIZE 10

typedef struct {
    char name[STRSIZE+1]; /* +1 to account for null-btye at the end */
    char lname[STRSIZE+1];
    char phone[STRSIZE+1];
    char bday[STRSIZE+1];
} record;

int main() {
    char search[STRSIZE+1];
    int i,nr;

    printf("\nInput number of records: ");
    if (scanf("%d", &nr) != 1) {
        printf("Invalid input.\n");
        return 1;
    }

    record rec[nr]; /* array of records */

    for (i = 0; i < nr ; i++) {
        printf("First name: ");
        scanf("%10s", rec[i].name);

        printf("Last name: ");
        scanf("%10s", rec[i].lname);

        printf("Phone: ");
        scanf("%10s", rec[i].phone);

        printf("Bday: ");
        scanf("%10s", rec[i].bday);
    }

    printf("Input the first name for searching: ");
    scanf("%10s", search);

    for (i = 0; i < nr; i++) {
        if (strcmp(search, rec[i].name) == 0) {
            printf("First name: %s\nLast name: %s\nPhone: %s\nB-day: %s\n",rec[i].name,rec[i].lname,rec[i].phone,rec[i].bday);
        } else {
            printf("Record not found.\n");
        }
    }

    return 0;

}

Answer 2

The numeric input leaves a new line character in the input buffer, which is then picked up by the character input. when numeric input with scanf() skips leading white space, character input does not skip this leading white space. Use a space before %c and it will help you cause if space is not used then a buffer added with value .so that use space before %c

scanf(" %c",&rec.name[i]);