Compilare: user.c:5:1: warning: data definition has no type or storage class [enabled by default] replace(char firstString[], char secondString[], char thirdString[]); ^ user.c:5:1: warning: type defaults to ‘int’ in declaration of ‘replace’ [enabled by default] user.c: In function ‘main’: user.c:11:23: warning: unused variable ‘i’ [-Wunused-variable] int k=-1, len1, len2, i; ^ user.c:11:17: warning: unused variable ‘len2’ [-Wunused-variable] int k=-1, len1, len2, i; ^ user.c:11:11: warning: unused variable ‘len1’ [-Wunused-variable] int k=-1, len1, len2, i; ^ user.c:9:15: warning: variable ‘file2’ set but not used [-Wunused-but-set-variable] FILE *file1, *file2; ^ user.c: At top level: user.c:38:1: warning: return type defaults to ‘int’ [enabled by default] replace(char firstString[], char secondString[], char thirdString[]){ ^ user.c: In function ‘replace’: user.c:68:13: warning: implicit declaration of function ‘abs’ [-Wimplicit-function-declaration] for(k=result+len1; k<len3+abs(len2-len1); k++){ ^ user.c: In function ‘main’: user.c:16:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%s", forbiddenWord); ^ user.c: In function ‘replace’: user.c:94:1: warning: control reaches end of non-void function [-Wreturn-type] } ^