c - Conversion character, and fgets() function didn't work as expected -

i trying write code find size of data types , here code:

#include <stdio.h> #include <limits.h> #include <string.h>  int main(int argc, const char * argv[]) {     // insert code here...      printf("choose 1 of following types relevant storage size\n(int, float, double, short, long, char: ");      char mytype1[7] = "";     char mytype2[4] = "int";     char mytype3[7] = "double";     char mytype4[6] = "short";     char mytype5[5] = "long";     char mytype6[5] = "char";     char mytype7[6] = "float";     scanf("%s", mytype1);     // fgets(mytype1, 7, stdin);      if (strcmp(mytype1, mytype2) ==0){         printf("the 'int' variable size %lu\n", sizeof(int));     } else if (strcmp(mytype1, mytype3) ==0){         printf("the 'double' variable size %lu\n", sizeof(double));     } else if (strcmp(mytype1, mytype4) ==0){         printf("the 'short' variable size %lu\n", sizeof(short));     } else if (strcmp(mytype1, mytype5) ==0){         printf("the 'long' variable size %lu\n", sizeof(long));     } else if (strcmp(mytype1, mytype6) ==0){         printf("the 'char' variable size %lu\n", sizeof(char));      } else if (strcmp(mytype1, mytype7) ==0){         printf("the 'float' variable size %lu\n", sizeof(float));      } else {         printf("incorrect choice\n");     }      return 0; } 

my questions are:

1. why xcode didn't accept conversion character except %lu, instance have tried '%d' 'int' statement getting warning argument has type 'unsigned long'?

2. scanf() function worked me, not fgets() function.

as understand size parameter in fgets() function maximum size can hold , not met (so if less size ok), why wasn't able use fgets() function instead scanf().

thanks.

for first of problem, sizeof return value of type size_t alias unsigned long, hence why "%lu" format works. however, should not use format, instead should using "%zu" specified have size_t argument (see e.g. printf (and family) reference).

as second question, have remember fgets can include newline (if fits) in string. have explicitly check , remove it:

if (fgets(mytype1, sizeof(mytype1), stdin) != null) {     if (mytype1[strlen(mytype1) - 1] == '\n')  // last character newline?         mytype1[strlen(mytype1) - 1] = '\0';  // yes, change string terminator }